I love my two Ultima 2 4000's. There is no maintenance other than flipping a lever every once in a while.. and are quiet and should last forever especially if used indoors. They aren't cheap though, but are worth the price for a large tank.
The AC110 is a great value and easy to maintain, but quiet they are not. Eheim Classic series (2213, 2215, 2217) are very quiet and last forever, but are more work to maintain and are about twice the price (2217).