I agree with the Koralia's, I have Seio's (M2600, so there is a big difference
) but the fact that the Koralia's come with a magnetic holder for the prices you can't go wrong...suction cups ALWAYS fail sooner or later. That and the power draw on Koralia is generally lower than the Seio.
Actually, I am upgrading to Tunze 6025's, you may consider those...a little more expensive but well worth it for worth the $60ish price tag (MarineMadness or eBay)...they can be modified to run at double their standard flow rate.