I voted Thief since I find it the most useful when used by the MH and sometimes the AI can be decent (and for some reason Thief has really good defense?? so it's also good in that regard)
Mage is pretty good but I prefer using physical attacks to magical attacks on my MH, Tank is better as the MH (and it causes quarrels a lot but it hasn't done that much in my case), and Flower is the same case as the Tank except I'd rather just have another Cleric tbh