I think that there needs to be a differentiation made when we talk about water cooling. There are two kinds of water cooling - the pre-built kits and the 'other kind'.
The kits do a very good job for what they are designed to do. I am not a fan but then I do not have the latest offerings to compare and comment on. Oh and I am not too trusting of some of the review sites and what they publish. So I tend to keep an open mind. The upside of these kits is that they cost quite a bit less than building your own personalised water cooling set up. That is the other kind
Once you step over to the wet side, there are heaps of options and decisions to be made. The first one is the most obvious but the one that is least made.
What is the work I want my WC to do?
Does it need to cool a seriously overclocked system for peformance gaming or crunching?
Does it need to be whisper silent for a HTPC set up in a TV room?
Does it need to bling so that my mates will go oooh and aaah?
There are many questions that could be added to the list of what work must my WC system do.
Now only once you have clearly identified what it is you want to do with the WC then you can proceed. So lets say you want a silent system because you share a room at Uni but you also like to game and therefore a bit of overclocking will be happening on the system that will be cooled.
The order of working stuff out is normally like this.
How much noise will be acceptable?
How much heat does my WC system need to manage?
The art is getting those two balance.
Oh yeah and how much is it going to cost me. WC is not cheap as a rule. And if you do start cheap you end up spending heaps more because the stuff you buy cheap does not have much longevity with the changes in hardware. So think hard about what you want to do.
Enjoy