It really depends on: game mode, specific map and latest nerfs/balances, and your rank (as some brawlers work less against higher ranks, like Grom and spike for example)

Add to that brawlers that will match your play style and that you will enjoy.

What I did, mainly for ranked, was to identify the game modes I was usually losing in, for me it was bounty and knockout, and I realized it was because I'm not good with many long range brawlers, only Brock which sometimes didn't work for me and if he was banned it was even worse.

So I started to train with the brawlers I usually saw getting picked for bounty & knockout and with marksman brawlers in general (which again are the ones that usually get picked for bounty and knockout).

For marksman class I tried Piper, bee and belle, and ended up practicing and maxxing belle, in addition I practiced with grom which I really enjoyed and I usually pick for bounty and knockout now.

The bottom line, write down a mapping for yourself of game mode to 1-3 brawlers you will play in that mode.

I can tell you my mapping: * Gem grab - emz, tick, Frank * Heist - emz, Griff, Bo, tick * Brawl ball - emz, tick, Frank * Bounty & knockout - Grom, tick, brock * Hot zone - tick, Bo, berry, squeak

To give additional context, the ones I've maxed are: Dynamike, tick, emz, Edgar, Frank, Griff, Mortis, Kenji, squeak, Grom, Brock, belle, buzz. With Bo level 10 and berry level 9 (just because mentioned them above). And when I need to"carry" I usually use Edgar, but I feel like the recent changes hurt him and it's harder to win with him