I came to bass from the guitar world and always used a Fender Jazz Heavy pick for both. I switched over to fingers a few years back and that is now my preferred style. The only time I use a pick for bass now is when I don't have control over the mix, and I feel like I'm not cutting through effectively. The band I play in runs everything through the PA, and there are times when my volume pot is on full and I still can't be heard well in the mix. Thats when my pick comes out, it adds a sharper attack and a bit more volume.
I feel that playing with my fingers gives me the ability to vary my sound much more than playing with a pick. With a pick I pretty much get one kind of sound; with my fingers I can change the sound by using a different part of my finger to pluck the string. I play both short scale and long scale and find the only real difference to be that shorties are easier to reach, and tend to provide a deeper sound.
Thump on,
One_Dude