Squire is meta in early progression through massacre (and brilliant in all levels below massacre) - hits hard nearly unkillable however if everyone plays a squire some maps become very difficult - summit for example.
DPS has a few options all of which are very viable:
Hunter with cat, hunter with Genie, squire with dragon, or monk with genie. I've also played with some awesome apprentice dps who 1 shot fairies in glitter massacre.
For optimum play currently I feel you want one dedicated dps, squire building walls, monk building auras and hunter building traps. I'm still leveling so have one of each but very rarely use my apprentice (they are great at nightmare level survival mode).
My advice is play what you enjoy i'm sure most combinations can be made to work.