Many people continuously commenting on other blog almost all of them are Nofollow comments. So my question is that is it advantages for PR or SEO except traffic possibility.? Please let me know.
Well, all those links will definitely help you in your process of search engine optimization but will not pass any link juice as Google considers only do follow links as a back links.
The advantage is that your links look more natural. I belive Google knows that all your links are artificial if they are all do-follow.
No follow links are important to your site as they give genuine picture in terms of getting back links. Ratio should be 20:80 of no follow and Do follow links.
Yes afcourse commenting on do follow blogs with high pr helps a lot. Its helps your site to get traffic and PR.
If that blog is niche to your category. Then it is useful even if it is with no-follow...It helps to get quality backlinks & also a good targeted traffic So try to post your comments on your niche category blogs...