Gammas? Only OP in DGs, if there's a DG with a lvl of gammas, then cut theyr numbers in half(spawn modifier?).
Basils? OP since theyr parasites do lots of damage, gammas got three times as much damage and i killed them at 150, while i couldnt kill basils, that at least in theory do only a third of the damage. And swarms are evil on basils. I mentioned gammas since the only differences between gamma bullets and basil bacteria blasters are:0.05 less rec on blaster and parasites.
Saws/SawXs, only OP because they completely stop you from turning, make it like 60-70 percent instead, i remember when i got killed by a swarm of AI(4 clefts, 2sawXs, 4slumbers). I could of killed the entire swarm, (or ran), but i couldnt since i couldnt turn, i couldnt escape even though i was 200 distance from a gate for about 2-3 minutes. They shouldnt completely stop turning.
BGs, OP since they take too long to kill, either reduce shield bank, or make them more vulnerable to mining.
Forgones are evil, they do quite a considerable damage, i can kill them 2 at a time(lvl 415), but it gets very hard since they push me, then look that i am moving away, then stop my slaves from doing anything by pushing them away and killing 1 by 1. Too powerful tractors. Oh and radars, they can see me from 2k when i am at 20 vis.
Nephils push and crit too much.
Rags are ok as long as they arent in swarms, when they are they disable your engine(energy) and make you turn, so only 360 weps could do anything(except that you cant thrust and thus get pushed out).
Seraphs, i have killed swarms of seraphs as lvl 72. They are ok as long as they dont come 10 at a time(paper shields).

seraphs in dgs would be cool for leveling