There are hundreds of different kinds of picks. They differ in thickness. They differ in shape and size and they all have different kinds of uses. For me, I tend to gravitate towards the medium pick. The traditional pick shape I use is this. This is actually a Dunlop pick. It's thinner than what I use. I actually use-- this is a Fender medium. This is the traditional pick shape. You can find them anywhere. One pick that I've come across for some reason I really like is this Cool pick. It's a medium. It's got a texture. This blue part it's got a grip, which I used to not like, but for some reason I like it now, and it's got a little bit of a pointier tip than the regular, traditional Fender medium picks.
I like to play with the back end of the pick actually. It rolls off the string in a totally different way then when you use the point, for obvious reasons. And it really gives you kind of a warmer sound. If I'm playing jazz or sometimes if I'm playing even on the acoustic guitar it really sounds a lot different. So that's with the back end of the pick as opposed to the tip. You can hear it. It has a much different effect playing with the tip as opposed to the rounded edge of the pick. And it also depends on the kind of you're using.
So a lighter pick, a thinner pick is more flexible. There's different gauges. They can go anywhere from paper thin to somewhat of a light medium. It just all depends on what you like. I find that the thin picks work really good on a 12-string guitar. Because of the flexibility of the pick, it tends to move with the strings and the more strings you have, like on a 12-string guitar, I just find it works better. A heavy pick is pretty immobile, not very flexible and so you get a duller sound, a thicker sound tends to bring out some of the bass notes a little bit thicker. Just experiment and see what works on your guitar.