I have tried every pick material, shape, most thicknesses and most brands in the 50+ years I've been playing. I have a whole bunch of guitar and mandolin picks.
My favorites for guitar for the last several years are
Gravity Gold Standard (teardrop shape) in XL size, 1.5 mm thick.
For mandolin-family instruments it's the
Gravity Gold Axis shape (triangle) XL size, 1.5 mm thick.
I still love my Charmed life resin and casein picks, and my
Wegen Bluegrass picks for guitar,
M200 for mandolin-family instruments.
I also like the Dunlop Primetime teardrop and big triangle picks.
The only picks I
don't like are thin picks (under 1.0 mm), nylon picks, wood picks, felt, rubber, metal, stone or leather picks, and Blue chips.