It depends really, do you have time to fiddle with a euro-reef? Most of the time you will have to make slight adjustments with a ER (Euro-reef)
Now I currently have a ER and love it, but I do love Tunze as well. High quality, German Engineering A+, and they don't break down like German Cars!
If you are going for a fish only setup, or with just live rock Tunze is fine, but if you are going to heavily stock it with fish and a lot of corals ER RC series is the way to go. Granted you will pay for it with the price difference.