Paul, After years of no-picks, I hate 'em. I prefer the natural thumb! However, when I did use a thumbpick, the way I chose them was to just go in the store and try them on. Never had a particular brand that I favored. Whenever I got one that was too tight I would hot-water it and put it on something a wee-bit larger than my thumb and leave it there a while. Never tried to microwave.

Sorry about your nail troubles. I generally leave my thumb nail short and use the finger-meat to plunk the strings. To each his own! ;D

khandu