Pick heroes you are comfortable with and what helps your/counters the enemy team.
Don't give a shit if ppl say don't play x y z hero... if you like playing them and you're good with them, play them
In the current meta don't bother with doomfist - he's either broken (not in the good way) or just really weak from the heavy nerfs after his release
But I agree with the other comments: play whatever you want lol
Your team will flame you for picking widowmaker and hanzo. You might also get flamed for picking symmetra, sombra, and torb (When you're not defending)
So you can play these characters, just don't go into team chat unless you want a brutal fisting
symmetra is the only character that's not worth it, any other character is worth it, my favourites are widow, genji, tracer, there's something fun about every character (except sym), you really should play everyone (excepto for sym)