I think it's very personal. I do find that a lot of speed players tend to use thicker, smaller, pointier picks. I started using Jazz Stubbies (the purple rounded ones) some time in the early 1990s. I began a quest for a new "permanent" pick probably 8 or 9 years ago, and nothing has fully satisfied me for long. What I'm using right now is satisfying me for right now, but I don't know if that will change in six months, a year, five years, or whatever.
What I'm using right now is the Flow 1.0 picks. They are full size (maybe a touch wider than "standard"), and I think they're made of Ultex. I have tried (not a complete list):
Red Bear Li'l Jazzer - First one was amazing, but broke after about 2 years. Second one had a slightly different shape and texture I didn't like (they're all handmade), and I didn't want to have to adjust like that every time I got a new pick. Like $25 each and you wait two months while they're made
Max-Grip Jazz III - Felt great, but too much rough pick noise for my taste. Great for chugging, not for lead.
Petrucci JP (Black matte/gloss) - felt great, sounded great, not enough grip
Ultex Jazz III - If I go back to smaller, thicker picks, this will be the one I go back too. Only thing really WRONG is the stale-piss color and it's the only color they come in
Tortex .73 (Yellow) Standard - I figured I'd try what The Man uses. Too much flex for my taste, but a great sound
Ultex .73 Standard 0 Still to flexy for me
Jazz III Black/red - no grip, dead tone. No "life."
Tortex Jazz III XL 1.14 - The 1.14 is really my sweet spot for Tortex and i like these picks, but they're not THE BEST for me right now. Love the purple. Grippy as hell.
Tortex Flow 1.14 - Again, really like these, but against the Flow they fall short.
Jazz III Stubby - my "true original" and the picks I used all through my gigging years in the 90s. Maybe I *should* try these again?