If you want to play more open positions, I'd probably go with either the Scotch or Italian. The Evans Gambit can be more positional, especially in the declined lines, and Black has so many ways to play a good game against the King's Gambit that it'd be a lot more work to study then the others. It's not a repertoire book, but I'd take a look at Paul van der Sterren's Fundamental Chess Openings to get a feel for any lines you're thinking of playing (it covers most openings).
Changing opening Repertoire

Hey Lukas,
With the Italian party you will have a lot of fun if you like to attack, and you will never be bored about it as there is always something spectacular. I really love it. Do not listen the ones who say it's a beginner opening, that's not the truth. ;-)
I'd say start with the Scotch: though your opponent may play Philidor's Defence 2. ... d6 or Petroff's Defence 2. ... Nf6.
If your opponent goes along with 1. e4 e5 2. Nf3 Nc6 3. Bc4 they might then play the Two Knights Defence 3. ... Nf6
If you particularly want to play the Evans you could create a seek with a thematic opening.

Play what you're good in during rated OTB games. That's when you aren't drilling but actually in the field to obtain practical results. Try out new openings only in practice games. These could be internet games, 30 minutes per side with your friends at a chess club, or whatever.
"Please no Ruy Lopez, I've had enough positional play"
Every game positional factors matter. Most tactical operations and king attacks are for obtaining positional advantages that last into an endgame. The defender against a king attack seeks to minimize their concessions, and if the attack was correct the concessions will be real whereas an incorrect attack will simply leave the attacker full of holes.
I'll say play the Scotch since it seems to be the second best compared to the Ruy, maybe the Evans' Gambit or if 3...Nf6 the Fried Liver with 4.Ng5. Just have preperation handy in case of 1.e4,e5 2.Nf3,Nc6 3.Bc4,Bc5 4.b4,Bb6!
The King's Gambit is also far from beautiful especially main lines where both sides have ugly weaknesses and pawn formations and white strains to obtain any advantage against reasonable play.

Play all of the openings you've mentioned in bullet and blitz games. I agree with the post above about getting FCO. Read the chapers on the openings you're playing. Another good book is IDEAS BEHIND THE CHESS OPENINGS by Fine.
Once you've played each opening quite a few times you will get an idea which openings you'd like to continue playing.
After choosing your openings, go over the games you've played with a computer to get an idea of the weak moves/mistakes you are making.
And keep these rules in mind when playing the opening-
From CHESS THE EASY WAY – Reuben Fine
TEN OPENING RULES:
1. Open with a center pawn.
2. Develop with threats.
3. Develop Knights before Bishops.
4. Don't move the same piece twice.
5. Make as few pawn moves as possible in the opening.
6. Don't bring your Queen out too early.
7. Castle as soon as possible, preferably on the Kingside.
8. Always play to gain control, of the center.
9. Try to maintain at least one pawn in the center.
10. Don't sacrifice without a clear and adequate reason. For a sacrificed pawn you must:
- A. Gain three tempi, or
- B. Deflect the enemy Queen, or
- C. Prevent castling, or
- D. Build up a strong attack.

I noticed big tactical problems with your play in this game:
Try not being so careless and irmprove your board vision.

Hi Lukas, I've been in the exactly the same situation as you, and I was given the advice to play open games, and gambit lines if possible. So I switched from queens gambit to kings gambit, and it really helped my game.
Yes, you'll have a lot of lines to learn, but it is not that big deal, and you'll benefit greatly from it.
Here is a link to forum thread that I opened few months ago, with the almost exactly the same dilemma as you:
http://www.chess.com/forum/view/chess-openings/advice-needed-about-open-games
I personally like the kings gambit, because it really accents the importance of development and initiative, and it forces you to play very agressive.
Don't worry if some opening is refuted on the GM level, we are long way from playing on that level.
Good luck!

The Scotch Four Knights is solid and leads to an open game with the possibility of tactics but nothing too crazy.
I've noticed getting an advantage in modern chess openings is difficult. In classical openings it is easier to get a good position and it is easier to keep the initiative. This should be reasons for e4 but there are a lot of blacks' s answers against e4.

Hey guys,
I will change my repertoire. I have always played d4 (2. c4 or 2. Nf3 with 3. Bf4) but I notice that e4 is better for my chess development. I want to play tactical openings because there are my problems. So what e4 opening should I play? Please no Ruy Lopez. I have enough of positional play. Only the ruy Lopez exchange variation is the variation in the Ruy Lopez which I love. Scotch, Evans Gambit, Italian or the beatiful Kings gambit? Which e4 opening is better for me or gives me initiative and attack?
But the problem is that my opponents rarely play e4. So I have to prepare against a lot of responses for example the caro Kann, french, sicilian. Do you know a book for hobby players which include an e4 repertoire?
After reviewing some of your games, Your study time would be better spent on tactics, and middlegame planning. You say you like to attack (What player at your level doesnt?) , but you trade at every chance?
But which e4 Opening is good for me? I want to play a gambit to learn initiative and dynamic play. Which gambit should be a good choice? Scotch gambit, kings gambit, middlegambit, ...
Do you know any books?

I think that on lower ratings, all of the above mentioned gambits are absolutley ok.The main difference between them is which one is easiest to force - kings and danish gambit are defined on the second move, while evans gambit is at move 4 - until then your oponent can deviate from theory and spoil your plan.
It would be great to read some books about it, but I have different method - Youtube videos - much more fun. While I'm eating my dinner I watch some videos, later I play some blitz on particular theme/opening, then I review my games, see what moves gave me problems and then I seek it out in the online base (www.365chess.com), to find where was I wrong.
Of course it would be much more better to read a book about an opening, but on my level I would rather read books about strategy, endgame, pawn structures...
Just my .2
Cheers

Gambits are not giving away material - they are trading it for time, development, initiative.
One thing is to hang a piece, and another is to gambit a pawn.
And I've heard lot of chess coaches recomended gambits for beginners, for example Dan Heisman - say no more. Sure, there are others who think different.

On gambits for beginners:
Well, I believe that playing "sound" and trying to play the best moves at a beginner is very important. When a player begins to lose because they play too solid, or is afraid to sacrifice a pawn in a complex position (instead of beginners who blunder every second move), then a player should study some gambits, and be ready to be down a pawn.
That was how I did: Caro-kann till 1600 ELO, and then I learned the smith-morra gambit (perfect, because I could keep my repertoire in place everywhere except the sicilian, and still play gambits often, like 25% of my games), then I began to evaluate material diffrently, and then I started to play main-lines, but not afraid to be down a pawn.
For OP: Don't overestimate preparation, and I say: go with the ruy. It's complex, and can be played (for advantage) for the rest of your life, whether you top at 1500, 2000 or 2800. Well, maybe 2800 is a bit too much, because the berlin is a tough nut to crack theoretically, but you got my point. I have no idea on what is theory, but I have played it for 3 years straight (from beginner to 2100 ELO), and I play it succesfully with both white and black. It is so complex, and you will always have a slight pull with white, and it's easy to switch between the exchange variation, the d3-lines and the (old) main lines. You can play gambits and open games against the sicilian, black is ready to take material and get mated! I recommend the Smith-Morra.

Actually, the main lines of the Scotch Four Knights open the position early and involve a lot of tactics if white gets to play an early e5, misplacing the f6-knight. I nearly lost to an opponent rated in the 1600s at the Eastern Open like this as black, although my opponent found a way to blunder the game back into my hands. I think it's a good opening to start with in order to work on tactics.

@ViktorHNielsen are you implying that the Ruy Lopez cannot be played for an advantage at 2800 level? If you are correct, then the entire opening 1. e4 probably doesn't work.

And no, don't play the Smith-Morra at 1100 level. Wait until 1500. In the Smith-Morra, you have to be able to handle the positions of the accepted variation, the d3 Maroczy bind variation, the 3...d5 line which often leads to an endgame where white is much better in spite of being a pawn down, the Alapin transposition, and more. That's entirely too much for a Class E-D player.
Hey guys,
I will change my repertoire. I have always played d4 (2. c4 or 2. Nf3 with 3. Bf4) but I notice that e4 is better for my chess development. I want to play tactical openings because there are my problems. So what e4 opening should I play? Please no Ruy Lopez. I have enough of positional play. Only the ruy Lopez exchange variation is the variation in the Ruy Lopez which I love. Scotch, Evans Gambit, Italian or the beatiful Kings gambit? Which e4 opening is better for me or gives me initiative and attack?
But the problem is that my opponents rarely play e4. So I have to prepare against a lot of responses for example the caro Kann, french, sicilian. Do you know a book for hobby players which include an e4 repertoire?