Another vote for both...
Fingers almost exclusively only on nylon,....
but on my electric I use a rather small Dunlop Jazz III pick or a 3.0 Dunlop Stubby, so I can "hide" it or drop it and go to a fingers only style like Mark Knopfler of Dire Straits.
I keep a selection of different picks on top of my amp and think of them like having various guitar pedals. I have a very thin floppy full sized pick for Johnson Brothers-style funk rhythm (where the pick hit is PART of the total sound) and a full sized heavy pick (my old favorite) so I can use the back corner for a rounder slop getting across string groups.
I think of them like drummers do various cymbals. I have favorites, but some picks are simply perfect for special effects and sounds I want to hear.
It all depends what sound I hear in my head and I now instinctively know what pick will give me the closest sound.
I almost use different picks to make up for not having a compressor onboard. It's strange, but it's just become habit now.
I wish I could use a thumb pick well....but I tend to use stay with a small pick and fingers for rockabilly/Scotty Moore/Brian Setzer stuff. I completely lose picks for a cool Keb' Mo' country funk finger pickin' groove.
If I actually think about my pick usage, I get myself confused. It's become automatic over the years.