I really like the Fluval Edge, but I'm thinking of a betta, and that one really wouldn't work in an Edge tank. That biOrb is awesome, but well outside my price range. The other is similar to a lot of brands I've seen, but the back side is completely covered, so it wouldn't really be viewable from both sides.
A 12 gallon long tank might work, if I could figure out a way to "hide" the filter on one short end of it. I'll have to give that some thought.