Go with the Behringer. I have used both in the larger formats and the Xtouch is way better for Logic. Plus the Faderport doesn't have a scribble strip, which will be handy using just a single fader.
Never tried faderport, but I have an x-touch one and I love it, but I admit it was a pita getting it working the first time. Since setting it up it works flawlessly and keeps my hand off the mouse most of the time which is great. I kinda wish I got the 8 fader, but then again, if you have to scroll to go past 8 tracks anyway, what difference does it make. Might as well save the desk space