I love my Gig-FX Chopper. It does great square wave, triangle wave, and blended trems. The rotary speaker emulations alone are worth the price of admission, and blow every single vibe pedal I've ever heard out of the very deep waters it can create. I just wish it had optional stereo in's. Makes integrating it into a pedal switching/looping system a bitch because of signal level matching issues. On the other hand it has one of the best buffers I've ever heard in a pedal, and seems to make everything plugged into it sound better even when it's off. So I just leave it in the signal path and use the foot treadle to control it.
The Hardwire stuff is also top notch, but I haven't tried the trem.