Good team developers are cameleons

Jeff Atwood thinks regions are evil:

No, I will not use #regions. And no, I DO NOT NEGOTIATE WITH TERRORISTS. Shut up.

I tend to disagree. I like being able to navigate through code blocks by scanning them and not using incremental search.
Besides, you can always expand all regions in code using a keyboard shortcut, and if it really bugs you, simply do a replace of "#" with "//#" and your problem is solved (until the next guy does the opposite).

However, I do agree with Jeff about working with a team, and that's why I think feeling that strongly about any coding habit is wrong.
Whenever I go into a new project I try to adapt my coding style to the existing style, even if initially I don't really like it.

That's why I don't think you should feel that strongly about anything and fighting about coding habits is useless - a good developer can adapt to any working environment.