Spent a few days off and on with my current faith / str character fighting the 4 kings. Boy was that brutal. After tons of weapon, armor and miracle combinations I finally beat them.
The first two I could take out quickly but half way through the third one my damage buffs would run out and I would start to get ganged up on.
I started out trying to use a +14 zwei but the R2 attack on it is just buggy as hell. I don't know if it is like this on PS3, as I never had a character use it on the PS3, but on PC if I do not let my character finish 100% of the attack animation before trying to do another action like use estes, roll or switch from two handed to one handed my character would not respond to any button inputs unless you mashed them a few times or pressed the block button. Every once in a while on the PS3 version I'd have my character do something similar if I queued up too many moves but with the zwei on PC it is every time with the R2 attack.
What finally worked for me was to start with a +14 claymore and then switch to a +10 divine claymore when sunlight sword and power with in wore off and use great magic barrier and out tank the last bit.
I've gone through the game with a dozen or so characters but I'd always stopped around 4 kings in NG+ simply because around that time I'd get the urge to try a different character build. --- Have you accepted Raspberyl as your loli and savior?