The best picks I’ve ever used, for both grip and tone, are BlueChips. I use their TD35 (teardrop shape) and TAD35 and 40 (triangles). My hands are very dry and I have a lot of trouble trying to hold on to flatpicks but, despite their smooth surface, the Vespel material doesn’t slip in my grip. No need to drill holes in them, or fanny around with stuff like Gorilla-snot or any of the other hickey-doos that are supposed to make picks adhere to the fingers.

Expensive, but for sound and feel they are the canine’s cojones.