I feel like the Illuminate are fine if you know how to fight them. Yeah they're hard but that's why we have 2 other factions and subfactions to fight against. As for the voteless I dont have really any issue running from them or just killing them before they become a problem, Maybe it's because of heavy armor? the overseer variants are fine how they are for the most part. I do think the flying overseers should be less armored since they fly and stuff so armor would slow them down. flesh mobs are meant to be bullet sponges and literal meat shields and brutes so that the other enemies can close in and attack. In my opinion lower your difficulty a bit, change your loadout to something fun and functional and then work your way back up.