I have an Antec 300 and love it. They just came out with a 302 with front USB 3.0 and better cable management. I plan on upgrading as soon as I have the extra cash. It doesn't have 2.5", but that is easily solved with a bracket, and as for water cooling, I have a Corsair H50 (sealed water cooling) but the case is roomy enough that I'm sure I could have done a DIY setup.
It's typical mid tower sized (couple feet high +/-) and it holds a ATX board just fine, I have an ATX Gigabyte Z68 in mine with 2 5770's and a wireless PCI card even, 3 HDD, 2 optical and a fan controller Room to spare.
The antec one is what I am looking for. Its light and doesnt seem to take upo much room. Seems good enough for water cooling.
This was also mentioned in a post. My mobo is and ASUS Sabertooth x58
Cons: More of a nitpick than anything else, the 120s it comes with only have the 3-pin connectors and Antec didn't ship any molex-to-3 pin fan adapters with the case, my motherboard only had one fan port on it so the other one is going unpowered until I order a splitter. Not enough to knock an egg off for but would have been nice if they had included the molex adapters or a Y-spliiter.