New
#11
Like everything else it comes down to features and cost. I'm partial to Corsair and just replaced my old H115i Pro with this one - CORSAIR - Hydro Series H115i RGB PlatinumH115i RGB
That said, as one who have used AIO (ALL-In-One) aka CLC (Closed-Loop-Coolers), since 2010, I'd suggest you check them for leaks every now and then. Don't get me wrong, I've never ever had one leak and I've had a few them, two currently in use now, but they do contain fluid so... And even if I did a pro custom water setup I'd still check for leaks.
Also, since water evaporates over time (and these can't be serviced), I put theme on a time change schedule where I replace them at least every 4 years. People will point to this as a negative but I could also point out that those big heavy air coolers warp boards and break connections over time. Neither is likely to happen, but...
Anyway, I don't want to scare you away, I love them, but its something you should know and think about.
Lastly at the end of the day pretty much all AIO's perform the same so it really is a matter of what features and price.
Good luck.