Four Kings I find the hardest NG+ fight in the standard game. DPS isn't so much of a problem, it's just my rolling sucks and there's no cheap way to beat them (enlighten me if there is!)|
Gwyn can be kited around the rock just to the left as you enter the room - poke him through it with a spear class and he'll go down eventually.
I tried for ages to parry him, but fuck me - that's a tough one to get right the correct number of times in a row.