Which gamer that you have played with has most affected the way that you play?
This is a hard call. There are several players I’ve had, both in my campaigns and as companions in campaigns by others, that affected me by being examples of how not to play. That is, don’t powergame to show up other players; don’t ridicule the campaign, the DM, the setting, or the NPCs to sate your particular brand of insult humor; don’t smell terrible; don’t go out of your way to create player discord; and the like. Aside from one DM, none of them affected me superlatively because I didn’t have to put up with any of them for long. So really this has to go to somebody who affected me for good rather than for ill.
I think I’m going to pick two people. They’ve both played together in my campaigns though they don’t travel in the same circles any more, and I’m writing this I’m in a campaign run by one of them and just finished a campaign run by the other. I’ve learned a lot about how to play and DM from both of them and I like to think the opposite is also true. One of them helps me to think creatively about what to run and how to manage a table, and the other encourages me to think critically about my settings and game balance. They both also have a knack for memorable characters and a willingness to rewrite rules that don’t work. These are all necessary approaches to a tabletop RPG, and I’m happy that I’ve spent enough time with both of them to borrow the bits of their styles I needed to make my own.