[GothicV]

My personal favourite is the Snarling Dog's Whine O Wah +.

I dont know if they still make it, but it has a seriously larger range as well as a much wider physical sweep than anything I've tried. It has 3 modes (lamely labeled of course) and they control the centerof the frequency range, from bass frequencies to treble frequencies. There is also a switch that is labeled tesosterone and estrogen. Testosterone is a much beefier sound, estrogen is good for the crazy funk "shaft" sounds.

An added bonus is the volume boost with adjustable volume.

I suggest you try one out if you can.