I can do both, but originally starting out on guitar I exclusively used pick when I switched to bass as my main instrument of choice.
I since learned how to use my fingers as well, using a combination of 3 finger plucking technique, acoustic classical guitar finger picking, faux index and thumb pressed together pick, as well as index and middle finger flamenco flicking technique, and actually prefer using my fingers now when playing electrical guitar, but on bass I still prefer that specific unique snappy emphasis on the attack you get from using a pick.
And as I don't really do covers but exclusively original compositions, and always have, it is entirely up to me whatever technique I want to.
That said if certain parts sounds better with the strings being finger plucked that is what I do, but 90% or so of the time I will use a pick.
My preferred pick both tone and feel wise is properly thinner and more flexible than what the average pick player would use for bass, but personally I feel that I get more control this way, as well, as said, I like the tone I get from it better, the pick being a Dunlop Tortex .60mm.
My default picking position being just behind (towards the bridge) where the 24th fret would be, of course though depending if I occasionally need a different tone, and holding the pick with a slight angle, meaning I hit the strings with a slightly rounder and slightly bigger area of the pick, which results in reducing the snap slightly, sort of ever so slightly dragging out the attack, making it slightly less sharp and tight, compared to flat picking, and adding a subtle scratching noise, which gives the tone a more raw dirtier quality, though I will frequently alternate to flat picking, that is holding the pick dead straight 90 degrees on the string, hitting the strings with the out most pointy tip of the pick, instead of slightly on the side, giving a tighter and sharper attack and a cleaner tone.
Both when using my fingers and when using a pick I only use the out most edge, sort of more so stroking the strings, rather than striking or pulling them them, which i think explains my preference for using a relatively flexible pick.
Again I feel that this way I get more control and prefer the tone I get from it, as well as it also allows me to play faster.
I do think using my fingers, especially with the fusion of different techniques that I have developed, would allow for a somewhat slightly more immediate and flexible pallet of different expressions, but I just love that somewhat aggressive specific unique snappy emphasis of the attack that only using a pick will give you too much to convert to mainly using my fingers.