Groove is more important; chops can come later.
That is the quote that says it all.
It doesn't matter how you get it. you have 2 hands, 10 fingers, and a bass, and make a sound. period. what kind of sound you get is more important than how you get it. and how you groove is more important than your tone.
So I would say, as you seem to be asking fairly intelligent questions, that you should practice all styles and find one that works better for you and you can decide if you want to drop any of the styles along the way. they are (from my limitted cerebrum):
1. pick (I play with a pick often, and there is nothing quite like it sometimes...)
2. thumb only (not my cup of tea, but.. hey what the ****

)
3. 2 fingers, index and middle (my perfonal fav for finger style)
4. 3 fingers (include the ring... )
5. 4 fingers (pinkie... almost no one really does this a ton, but it is done)
6. 4 fingers and thumb ... go hog wild
7. my new technique (probably not mine originally, but new to me): hold the pick with the thumb and index, and finger pick with the middle and ring... that way you can either get a finger or pick feel without having to put down or pick up the pick.
8. slap / pop
9. strum the bass with your index finger (I'ver resorted to this sometimes) like you were playing a guitar - imho only works very short term
10. you gotta be able to think of something. from the responses you've got above, most are just blowing hot air, and trying to start thier own flame wars for their own reasons - which usually mean that they are just flaming and looking for responses as an alternative to asking questions explicitly. why people like the implicit approach boggles my mind, but maybe that's just me.
11. ****, there goes my david letterman 10 top, i'm at 11!