2217 hands down. Last I checked, after you purchase the filter media for the XP3, the 2217 is actually cheaper. It's a model that has been around for YEARS, and has had phenomenal revues for a long time.
It's quieter than an xp3, is probably going to last longer than an xp3, doesn't clog as fast as an xp3 (all xp3s I've seen slow down after a little while, my 2217 can go 6 months without being cleaned and there's barely any noticeable difference in water flow), and water doesn't bypass the media in a 2217 the way it does in an xp3. You can also vary up what's in the 2217 as much as you want- take out a scoop of one media to make room for another, and don't worry about how much you can fit in each tray and the wasted space between them.