I have the Antec 360mm Mercury 360 which is a cheap AIO for under £100. Absolutly no problems with it and keeps 8700K overclocked to 5GHZ cool at under 75 degrees C in Aida and Prime95. The reason I thought I would check it out was the pump has a much higher flow than the others at 210 litres per hour.
I have also used the Corsair AIO's with the H110i GTX and again, very good with no issues at all on the cooling front. There are a lot of options on the AIO front now and as suggested the Alphacooler Eisbaer 280 or 360 are rated highly and apparantly you can extend the loop to your GPU at a latter date if need be with the quick disconnect connectors.
NZXT also but are a bit more expensive same with Thermaltake. ID-Cooling's Frostflow 240mm and the Cooler Master MAster Liquid Lite 240 are super cheap at under £50!!!
Lots of good choices out there now.