I switched my audio interface this week. I was using a Lexicon Alpha, which is a decent but low-cost 2-in/2-out interface. I replaced it with a PreSonus AudioBox USB.
In terms of recording clarity, they're both very good. But the PreSonus had several compelling advantages that swayed me toward buying a new interface:
(1) It's also a MIDI interface. This is huge, because it frees up a USB port on my MacBook Pro and decreases by one the number of boxes that have to sit on my desk. It sort of compensates for the lack of USB on the Evolver.
(2) The footprint is significantly smaller than the Alpha's.
(3) All-metal chassis, while the Alpha is mostly plastic.
(4) 1/4" headphone jack instead of the Alpha's minijack.
(5) Separate master and headphone volume controls.
(6) Phantom power, which I don't need right now, but it's a nice option.
If the Alpha has any advantages over the AudioBox, it's the spacing of the knobs. The AudioBox's knobs are tiny and closely-spaced. It does its job really well. If you can get by with 24-bit/48khz and two inputs, I highly recommend it, especially if you would value having a MIDI interface along for the ride.