I've owned both, stuck with Epson.
For the most part, it's like comparing Nikon/Canon SLR's. You can choose blindly, or you can compare every detail, but you get pretty much the same result either way.
I think Epson is more popular among fine art photographers, but that may be a relic of having been better ten years ago.
Very happy with my 3880. One comment... if you go down to the consumer model Epsons, per-page ink costs go way up. I upgraded from a 2880 mostly for lower ink costs, even though I print relatively little.
http://www.redrivercatalog.com/cost-of- ... nting.html