London system
Discussion- What Type of Openings Should One Play to Best Improve?
My opinion is that you need to be good enough at the things you like doing before you try to be good enough at the things you don't like doing. If you get to the point where you are very comfortable playing positions you like and beat people slightly above you at a good rate, then you should look into something else, something you don't necessarily like or feel comfortable with and start learning and playing that. Rinse and repeat.

When you're trying to improve your overall chess ability, choose option 2: play openings that force you to work on all aspects of your game. This is because, like you said, you can't always control the flow of the game, so it's important that you're at least somewhat balanced and capable of navigating a wide range of positions.
But when you're playing (or preparing for) a serious tournament where the results matter, choose option 1: play openings that you're familiar with and that create positions that highlight your strengths. Don't go experimenting with a brand new strategy when it's a serious game that matters.

For me, the openings I play are openings that give my opponents less opportunities to trade pieces with me as less pieces generally mean easier positions to play. If I want to get better, I need to be able to beat people with great middle game plans as that's generally where the outplaying happens in chess. With more pieces, the easier it is to win (generally), and easier to lose (generally).

~I think play into your strengths to start with, usually you enjoy the games better and obviously more wins. There is so much to develop in one style and complimentary openings and systems are also good to study and expand your repertoire which allow you to switch if the position or pattern changes.
eg. The Nimzo-Indian and the Ragozin are one complimentary example.
~Better as White to stick to just playing for example 1.e4 or 1.d4 and don't switch as there is simply too much theory out there for the first few years.

Personally I think you should play openings where you know the common ideas and themes. For example, the basic idea in the Colle is to play triangle and then e4 and go all ham on their kingside if possible.
Go for those that obey opening principles (control the center either from a far or directly with your pawns) Some of these opening include
- Nimzo
- Ruy Lopez
- Grunfeld
- Sicilian
- Italian
- Caro-Kann
Just to name a few. See a complete list of the top 13 best chess openings
Once you start playing professionally you may deviate to other openings that break opening principles as seen with many grandmasters.
It often takes less effort and is more satisfying to get from good to great than mediocre to good. What I mean is stick with, and improve your playing style and what you enjoy and feel good at. Look for opportunities to improve your weaknesses and game generally within that context. Or make sure you bring it with you, what I mean is do the positional openings have tactical and attacking lines that suit your style.
Recently I've been thinking to expand my opening repertoire, and that got me to the question... what type of openings should one play to best improve their chess?
I see 2 logical answers here... the first is, play openings that support your style of play, the second is to play openings that force you to look at the style of play you're weaker at. I'll give a detailed explanation below:
1. Openings that go with your playing style.
This is the obvious solution, if you like attacking and are a good tactician, go with sharp openings that lead to what you are best at. If you are a more positional player, play openings that are solid, but aren't very sharp or tactical. This type of thinking works well, since it usually leads to positions that you are experienced at.
However, there are some drawbacks; if you are a good tactician, for example, but then get into a very positional endgame, you'll be more likely to lose because you don't have much experience in positional play.
I used to play 1. e4 as White, but I'm not a very attacking player. It's been almost a year since I switched to 1. d4 as White, and it gave me much better and more consistent results.
2. Openings that force you to look at the other style of play.
This way of playing is a bit different, the philosophy here is that if you play openings that lead to positions that you are inexperienced in, it will force you to get better at those positions/playing styles, therefore shoring up your play.
There are some drawbacks, of course, when trying this at the beginning one might lose quite a few games, but eventually one gets better at that playing style, and manages to greatly improve it and shore up their play. There's also the option of temporarily trying this, then going back to openings that suit your style, but you'll have improved in the other style of play, and you'll be a better player overall.
Like I said before, I'm not a very attacking player, but recently I decided to play some more aggressive openings as Black, I switched to playing the Sicilian and King's Indian, and now my tactical play is much better.
So overall, here's the main question:
What opening strategy do you guys play, or prefer? Do you play openings that suit your style, or do you try to shore up your weak points by playing openings that expose your weaknesses?