I have two eheims, both which are silent and very cool running.
My biggest complaint with the eheims is plumbing them. Being that the fittings aren't metric, it takes a bit of fiddling and experimenting if you want to hardline it with PVC. If you're just going to use clear/braided vinyl hose, then it's not a problem: barbed hose fittings are included. It's just too bad the Eheims are so expensive.
That being said, despite being noisy and inefficient (they use more watts and put off more heat) I hear the MAGS are bulletproof, so either way you go you'll get a decent pump.