Ive had the Lehle Dual SGOS, Radial Big Shot, Voodoo Lab Amp Selector and a number of Stereo pedals that I've used to split signals before.
If you want switching functions, in my experience, the Lehle is the best. Its one of the few that offers midi integration and has best overall tone preservation and lowest noise of all I've tried. That being said the others I've had were quite good.
I'm currently running a 3 amp rig using both outputs from a Boss MS-3 and a Radial Bigshot to split out for amp #3 and it works great. The big shot is a passive pedal so if you engage the iso switch, you will get some output loss on output B. I found if you throw a HumX on the power cord of the amp, you dont need to use the ISO switch, thus no tone loss and no ground noise.