lots of ppl will say corsair, but i disagree. i HAD an h100i, and installed a few others for friends. have had nothing but problems with them. mostly soft and firmware issues.
i switched to a coolermaster 280L nepton 280 mm and am very happy with it. the only problem is that it doesnt have software support, but thats not an issue for me because i use the rog software from my motherboard for it. Just make sure your case will fit a 280mm rad.
if not, and if you want software controlled fans and pumps, from what i have read, the NZXT Kraken x61 is really nice