xotic bass bb preamp of fulltone bass drive mosfet?

Well both are TS clones and will have many similar tones. The BB can get bassy-er and more trebley than the Fulltone, but I didn't find either to be appreciably different from the other. Both can have the TS mid-hump, can be a clean boost and can get very overdriven.

Might as well throw the Hematoma and the VoodooLabs Sparkle Drive into the mix.

 

I haven't used one but - the HBE Hematoma has seperate overdrive and clean boost channels that can be used independently or cascaded. It seems like that would be a 2 for 1. Plus it's only $154 brand new!