Which is the leading facebook module for Drupal 7 a complete site integration? There are 3 main FB integration modules for Drupal 7;


FB
FBconnect
FBoauth


There are tons of discussion threads around the net and drupal.org describing the pros and cons of each module. From all these threads, this is what I've gathered. If all you want is FB login capabilities for your users. Then FBoauth is your best bet. FBconnect does a few of the 'other' features pretty well but requires some bug fixes to be stable. FB is great if you want APP integration for your site. But my question is;

If you wanted your site to do;


User Registration
Content Posting to Wall Stream
Comment Stream 
Friend Inviting


Which is the best module to be able to have those features built into your drupal site?
You need FB. It offers all what you need.

I've been in the same dilemma and went with that one.

I suggest to try all of them and see for yourself though. Don't waste time with modules which offer third party integration - they rely on registration on those websites and usually paying a fee to them. I think it's silly registering and paying for a third party service in order to use another (free) third party service.