Single or double?
i personally think the copper/brass stock-ish radiator is the way to roll. yeah it's more expensive, but it's also a known entity and you can get a shroud for it and everything just works together right from the jump.
the champion rads are attractive at half the price. and i know guys that have 'em and love 'em, and haven't had a problem with them. and i've installed a few at the behest of clients with relatively little drama. but to me, that good money spends once and gets the job done the first time.
the alternative being one of the higher end alum. jobbies and a shroud with elect. fans, which is distinctly not my jam.