Good to see thd community helping out newer and younger players Keep up the good work everyone.
My suggestions would be based on what event or activity you are doing:
Bounty - Obvs the UAF and UAF Airborne as they are bonus
PVP - Flatline, Mandrake, Caine, Keel, Halo, Phalanx, Kobold, Ronin, Odachi, Kuno, Matador, Heimlock, Bolt, Moss
PVE - Basically the same as PVP + Hivemind, Butters, Nightningale, Cinder, Dogface
AW - Beck, Saphyr, Heckler, Kurtz, Baron, Richter, Razorback, Wesson, Cara, Hivemind
(For AW those are the top 10 heros in the game for power when 10* 5 bar, depending on how much you like war could be a suggestion to start working on those
Keep playing and you will keep growing, most of all have fun, make sure to reap the rewards of bounty starting tonight! Find yourself an alliance that is active and participating so you get good rewards