Which forum to choose for better traffic?

[Jake]

Bear in mind that the search engines hope you will not create links to your own site, rather interested users will create them after visiting your site, to avoid any warning messages and to get the best effect you need to get a diversity of link sources, don't focus on a single type or it will look unnatural.

This site helps generate searches for pages likely to match your sites subject matter:
http://dropmylink.com/

typically you have to first become a good citizen in a forum before getting full link making privileges, often you can put sales copy and a link in the post signature which would not be allowed in the main message.