best plugin for comments?

Hello,

I’m trying to figure out what would be the best way for people to comment on my posts. I have looked at plugins like User Photo, Mingle,and Profiler. I have also looked into Gravatar but im not sure how to direct my readers to create a profile on Gravatar, and they would still need to add their email address every time they want to comment. Is there a way for someone to sign in to Gravatar through my website and just comment without needing to enter the email address for every comment? that would be perfect!

Basically all i want is for people to comment without needing to submit their email address every time they want to comment and also to be able to add an image for their avatar.

thanks