Maya's ability is far more orientated to gameplay with friends. She's quite a "teamplayer" style character. If you are going to play with friends, play as Maya.

Zer0 is an assassin, so it's obvious he'll be better alone. His ability helps solely him (I suppose it could be used to help the team but that's being picky). If you play on playing more single player, play as Zer0.

Maya's power is to pick an enemy up off the ground so you or your friends can shoot the enemy. Zero's power is to turn invisible for a few seconds, but he also sends out a decoy upon activating the power. I chose Zero and my friend chose Maya. I think Maya's power looks way cooler than Zero's.

when i get it im going with comando but out of thoes two i would pick zero