what is the best opening to use as a beginner with a bit of experience?
As a beginner, you shouldn't worry to much about exact opening lines as your opponents will not play the main lines anyway. Play something "mainstream" (Ruy Lopez, Italian, Queens gambit etc.). Focus on opening principles. Everything you need to know about the openings as an improving player can be found here:
https://www.chess.com/blog/nklristic/surviving-the-opening-first-steps-to-chess-improvement
By the way, if you need a general guide which can help you improve your game, check this out:
https://www.chess.com/blog/nklristic/the-beginners-tale-first-steps-to-chess-improvement
You're welcome. I hope it will be useful to you. Little by little just by playing you will learn a few moves and at least where the pieces belong on the board . You will not know the move order but that is fine, the exact opening lines below expert level are not really essential.
For instance I don't really know too much about exact openings. I know some lines for a little bit but then I improvise. 
Berlin defense/Sicilian defense for black, Ruy Lopez/Italian for White
Maybe the scotch/scotch gambit? It's pretty easy, get people a bit off track with opening lines and ends in a pretty open tactical position
I honestly don't know the best opening lines and responses vary, but I like it as white, as black I usually do some financhetto and counterattack
Regarding the OP's interest in "...openings that are attacking-focused and often result in an open type of play."...
I believe the Italian Game would be a very good choice, appropriate for a beginner-novice, or any player for that matter. It's an opening you can grow with and play for the rest of your chess career, including at the highest levels...
In this regard, for an instructive openings repertoire book which is targeted to the beginner-intermediate player audience, I recommend My First Opening Repertoire for White by Vincent Moret which features the Italian Game. Also, his instruction for how to play the Grand Prix Attack as White against 1. e4 c5 (Sicilian Defense) is outstanding, the best I have seen. Check out my review of the book here (search 'Moret')...
Good Chess Openings Books For Beginners and Beyond...
https://www.chess.com/blog/RussBell/good-chess-openings-books-for-beginners-and-beyond
Excerpts from Moret's White and Black opening repertoire books here...
My First Chess Opening Repertoire for White...
https://www.newinchess.com/media/wysiwyg/product_pdf/9033.pdf
https://www.google.com/books/edition/My_First_Chess_Opening_Repertoire_for_Wh/cdUlDAAAQBAJ?hl=en&gbpv=1&dq=my+first+chess+opening+repertoire+for+black&printsec=frontcover
My First Chess Opening Repertoire for Black...
https://www.newinchess.com/media/wysiwyg/product_pdf/9050.pdf
https://www.google.com/books/edition/My_First_Chess_Opening_Repertoire_for_Bl/GL88DwAAQBAJ?hl=en&gbpv=1&dq=my+first+chess+opening+repertoire+for+black&printsec=frontcover
Chessable also has courses based on Moret's two opening repertoire books for White & Black....
https://www.chessable.com/chess-openings/s/moret
Here, a repertoire in the Italian Game for play at the highest levels, and a recommended follow-on to Moret's book...
Winning With The Slow But Venomous Italian by Muller & Souleidis...
This repertoire is focused on the 4.c3 /5.d4 variation of the Italian Game - The Giuoco Piano, which is also the main line of Moret's White repertoire book.
Read the authors' preface and introduction (book excerpt) here.....they also explain why they prefer it over the Ruy Lopez (Spanish Opening)...
https://www.google.com/books/edition/Winning_with_the_Slow_but_Venomous_Itali/HokfDgAAQBAJ?hl=en&gbpv=1&printsec=frontcover
https://www.youtube.com/watch?v=Szr8mNLKtPg
https://www.amazon.com/Winning-Venomous-Italian-Easy-Grasp/dp/9056916742
Finally, another very good introductory repertoire book on the Italian Game by John Emms - "Beating 1 e4 e5". Emms' repertoire focuses on the modest 4.c3 / 5.d3 variation.
Collectively, the books above should teach an amateur player (and beyond) essentially everything they need to know to play the Italian Game at a high level.
for openings generally, you might also check out...
Chess Openings Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond
I have no affiliation or connection to New In Chess whatsoever. I simply view these recommendations as being good and appropriate books for the OP's purposes.
I like the Italian, Ruy Lopez, Queen's Gambit, Scotch, or possibly Danish Gambit (if you want to sacrifice two pawns for a huge lead in development and an attacking, open position) as white. As Black, I play the Berlin, the Giuoco Piano (avoids the Fried Liver at lower levels), the Slav, and the Semi-Slav.
Queen's gambit and Italian are often recommended
mind you, a very basic setup in classical openings- italian game, caro kann, and slav defense helped me immensely when i took my first steps in the game
but, eventually, what i realized after hundreds of games is that my opponent and i were “out of book” by move 5
so my “openings” are now this:
as white- 1. d4 ... 2. c4 (almost all the time)
vs 1. e4 ...c5 (ditched caro kann and c5 just felt “more to the point” and fits in with my wanting to “play for the center”)
vs 1. d4 ...d5 (sometimes i will move a knight first)
but, essentially, any classical opening will serve you well