I have both Alphacool XT45 X-Flow and HWL GTS XFLOW rads in my case.
The HWL rads are very efficient but the width required me to Dremel my case to fit it in the front. Very good quality and really good at cooling with low to medium fan speeds. Most models only have the two ports.
However, there are times when you want to cut back on fittings and could really use a mutli-port rad. HWL has their SR series but you still have the width issue plus it is 60 mm deep.
The Alphacool XT45 rads offered me that extra flexibility. They are built well with a quality feel to them and are pretty decent cooling-wise.
They work well at low to medium speeds (when used with high SP fans), but are not as efficient as my HWL GTS rads.
I originally had a 140 XT45 X-Flow on the exterior rear fan set on exhaust. The extra ports allowed me to add a temp sensor, a drain, and an air bleed valve without using additional fittings.
The bleed valve was the high point of my system and also was used as a fill port. Very handy.
I now use an Alphacool 280 XT45 X-Flow radiator mounted externally. I use two Corsair ML 140 fans on push only.
When added to my loop (with 2x HWL 280 GTS XFLOW rads) I see a 25% to 35% lower delta (depending upon tests being run and ambient conditions).
All fan curves run off my Aquaero. I have a Quadro added as a remote device on my external radiator that links to the Aquaero.
You could probably get a better price for the HWL rads as the Alphacool can be a little pricey.
However, I am very happy with both of my Alphacool rads, and I am still holding onto the 140 XT45 for another build.
This is a good spot to see some very detailed reviews on radiators: https://www.xtremerigs.net/2015/02/1...or-round-2015/