Interesting discussion. As an almost exclusively fingerstyle player since forever, I've recently started using a pick regularly for the first time in about 30 years as I'm currently playing in a 3 piece post punk-esque band (with a couple of guys I also haven't played with for 30 years!), and I needed a bass sound that is fairly aggressive and will cut through the mix - think JJ Burnel Raven era, gritty but not quite as full on at his early sound. Tone wise, there is no way I could get that sound with my fingers.
So far, I'm finding that a .88 or 1.00 mm tortex pick is giving me the right balance between playability and tone. Any thinner, and the sound is too thin, any thicker and it becomes hard to play fast 16th type runs with precision and it looses that bite that I'm after. I'm running my ACG bass through a Bassrig Super Vintage preamp, pushed just past the edge of breakup with some bass rolled off, into a cheap TC electronic BQ250 head set flat, and I'm very happy with the sound I'm getting - punchy and bright with just enough clank - it sounds spot on in the mix.