I personally prefer Victorinox. I have a couple of Wengers, and they are good knives, but the fit, finish, out-of-box sharpness, smoothness of pivot action, etc., seems superior with Victorinox.
Another interesting thing is that the standard-sized Wengers are a bit smaller than the standard-sized Victorinoxes.
Both brands are excellent, but I know from experience you can't go wrong with Victorinox.
Jim