70 lvl with most mail gear and a few leather/cloth. With shields ofc (really if you have good 2h - drop it and get any 1h and a shield and you will suffer less damage)

Before I have taken shield - I had 1 more anti-calss - hunter. 1 decent geared hunter was doing so much damage so I had to heal myself most of time against him. Once I have taken a shield - easy

So to be honest now my anti-class is a3 gear with best jewelry and trinkets. Had hard time at BG y-day against 2 such hunters and a rogue. Damn hard!
A few days ago I have been fighting against 2 warriors geared with a3/BT and getting some heals for random people. Man thats insane damage, I could kill them only with ns/em CL combo.

Well if count that the enemy has same gear them my anti-class is mage. Dragon breath, blast wave and some other aoe is damn annoying. Mage is easy to kill but he does pretty good damage with listed spells and a few AEs.

Talking about rogues. They are annoying but not critical. With poison cleansing totems up I can easily heal through the damage and kill them once I have time. Only thing about them is that you have hard time killing them. Cloak of Shadows + cheating death + vanish make them annoying as hell but pfff nothing more.