Welcome to the board
if you use the search function you will likely find literally hundreds of threads on this very subject
If you want a wah that is fairly simple to operate and you don't want to worry about mechanical parts breaking go with an optical wah
that said the Snarling Dogs wah sounds incredible but, it has tons of mechanical issues if you buy be prepaed to learn how to put it back together from time to time...lol
Morley has a very nice line of optical wahs...
http://bass-guitars.musiciansfriend....dal?sku=150750
I myself prefer the Ibanez Weeping Demon wah....it is not marketed to bass players however it does have bass specific settings and it does old school as well as new school with auto shutoff...as well as being able to adjust the filter sweep...it allows for a lot of user custom settings
http://guitars.musiciansfriend.com/p...dal?sku=150344
YMMV as some people with active basses have complained about it....but i have several active basses and it works great with them
good luck