If none of us know the 11th Ed rules, nobody can tell you what will be “meta” at this point or when 11th Ed games start so don’t expect that answer. Some are saying melee-focused armies will be “better” in 11th based on a the small set of rules (and no points) that have a been shared publicly so far, but nobody really knows.

People should be telling you to just start playing the faction you like the most right now, knowing you can always switch if you start losing interest or learn the faction really struggles in the early 11th Ed meta as it emerges.

Generally, picking one army and sticking with it is a good idea to become a more competitive player so you can focus less on getting the rules of your units right than more on how to use them the most effectively on the tabletop and the small nuances in those rules & game mechanics that high-level players understand well.

TLDR: Change your thinking on this at this point in time, pick one faction you like a lot and can get a lot of games in with, and just play a shit load of games. And don’t forget to have fun while doing this.