Are there no set rules for this? I've seen people on Level 6, with thousands of 'points' not have the title but then some people who have only joined a few weeks ago and answered 100 questions with it. I'm not dying to be one, just trying to understand who decides etc.
Rev
Favorite Answer
A Top Contributor is somebody who answers frequently in a particular category and achieves a minimum Best Answer percentage with those answers. There are no extra privileges in being a TC.
While the exact formula to earn a TC badge is a Yahoo! secret, it is known that in order to earn one you need to answer a minimum number of questions weekly in a particular category (perhaps 30+, and Polls & Surveys and Jokes & Riddles are not eligible categories) and get a minimum BA% on those answers (roughly 12%+), kept up for a few weeks in a row. Categories which are not very busy will require fewer answers to earn the badge than one that is popular.
Once a TC badge is earned, you will need to maintain the same minimum level of answering or you will lose your badge within 1-4 weeks (5 in rare cases).
Anonymous
A lot of best answers in one or more categories. Choose one or more categories you know a lot about and concentrate on them.