Gonna disagree here, Moze is easilty the most fun of the "summonable death machine" classes. Putting dual nukes or dual railguns on the mech was great fun, actually doubly so becuase the skill was a powerhouse throughout the entire playthrough, even in endgame at mayhem 10. It would still melt vs corrosive enemies, but that's what elements do.
Roland's turret was only actually useful vs Crimson Lance during Armory runs, and only if you had it on corrosive level 5. Completely worthless otherwise.
Axton's turret was irrelevant on TVHM/UVHM, basically getting demoted to a slag machine, dealing pathetically low damage. The shield would literally collapse after getting hit by a single bullet and the nuke deploy was dealing like 15k damage with most basic mooks having 30m hp on UVHM OP8.
Deathtrap might as well not have existed. Gaige only had anarchy going for her.
Wilhelm's drones were the "boring but effective" type. Dealing respectable damage on TVHM, but mostly because the health scaling wasn't pants-on-head retarded and slag did not exist.
I haven't played enough of Doppelganger to really have an opinion. Couldn't even be assed to cheat a high level character in, but I heard the skill was shit and the most broken build was centered around money stacks.