I can concur with most of has been said. I love adding fingernail occasionally, find it more natural sounding than a pick, and more variable with position. I am always paranoid about my fingernails - whenever they chip from projects around the house, I freak! I keep clippers and nail files all around for such emergencies!
My techniques include, in order of usage:
- Two-finger with occasional fingernail for effect, especially on low strings.
- Thumb plus two or three fingers like a classical guitarist, great for chording, often with some fingernail
- Pick
- Hybrid picking using pick on low strings and remaining fingers for higher notes
- Thumb only for dub-like sounds
- Slap/pop - not my specialty, but getting there.
- Right hand hammer-ons and pinch harmonics - still working on these!