In my opinion dont get a pedal unless you really need it, i have bought several pedals on a whim and i sold them quickly
However if you are in the market for some pedals here are a list of pedals that I found to be good.
Aphex Punch Factory
Aphex Big Bottom Exciter
Fulltone Bass Drive Mosfet
and finally the Tech 21 Sansamp Bass Driver
And when you buy pedals, make sure you read alot and if you can, find a store with good testing capabilities and give them peds a shot first.
+1 on the aphex pedals, and for sansamp, I use the acoustic DI instead of bass di (fretless and wants more control over tone and dont really need drive).
D.Don
] then I again stopped using effects for a few years and again reassessed my playing and them dove back into the world of effects, but now I really know haw to utilize them to compliment what I'm playing and when to turn them all off and/or just leave them at home.