I've been using Zain a lot lately. I love using him on certain maps more than others like Spearhead. The PF51 is decent for CQC. It feels a bit unpredictable. Sometimes I can laser someone while other times the recoil and spread are wild. I don't get it. Same with it's damage. The damage range has a harsh drop off.
Zain
Rorsch Mk4 with either the ghost hybrid or the Target 4.5x scope
PF51 sidearm (after using this I wish that we could have SMG's as sidearms)
Ammo Box
Prox Sensor
My other go to is for pushing and more aggressive CQC is:
Mackay
M5A3 extended mag, XDR Holo, LWG grip, and Warhawk muzzle or MP9 with drum mag
PF51
Ammo
Prox
I used Liz quite a bit, but with the new Rail Gun I feel like I can do more by playing other characters when using that versus her rockets.