Well if you intend to cool the GPU's and want to stay with only one of those two brands you would have to go EK for full cover blocks. Is there a reason you are only going with one brand for everything? If there is, then here's my comparison of the two:
EK XTX Line is better all around, but the Swiftech MCR XP line is just as good at high fan speeds and is somewhat thinner. (Reference: http://martinsliquidlab.org/2012/04/14/360-radiator-shootout-summary/
But, the Alphacool line beats both. The ST30 is excellent at low speeds, UT60 and Monsta are great at anything above 900 or so RPM.
The Apogee has one of the easiest and most consistent mounts available, and both perform roughly the same. Unfortunately Stren's testing is no longer available on this site and I don't have a link to it at the moment.
Once again the current best CPU block is the Koolance CPU-380 by over a degree C.
I personally use the Swiftech MCP35X and with it set up for PWM I really like it. It is a bit louder than a Laing D5 but has more pressure.
EK makes the broadest range when it comes to fitting non-reference designs, and may be your only option for full cover.
Pick whatever looks best to you. Some like Tube Res's some like Bay's. It's all personal preference really (Well it is a bit easier to fill a tube res).
Order some Durelene from sidewinder, super cheap and I believe has had less incidence of plastecizing lately.
Strongly recommend compressions, Bitspower are excellent but rather expensive. Big fan of my Enzotech fittings, very solid and mid priced.
Gentle Typhoon AP15's are still the best performance/dBA available, at least in the commonly available fan category.