Which do you prefer to comment on a blog, an old article with pr or to comment on a fresh article but no pr?
I prefer that when I'm compelled to offer my opinion about what I just read on a blog article, that I might contribute something intelligent in the form of a blog comment otherwise, I keep my mouth shut and don't waste everybody's time trying to convince them that my web page is important because the search engine thinks it's credible enough to highly rank; aimlessly dumping link infested babblings all over the Internet for no purpose other than a mediocre-poor attempt at positively influencing my web page's off-site ranking factors.
You gotta' think out of the box to claim most your competitive SERP (search engine results pages) victories. Be innovative. Highly rank your web pages. Do it with a little bit class. Study and practice search engine optimization.
I guess it is a matter of ethical preference. I tend to do both. Only because I am very opinionated and I never know when one of my comments will help someone. I also do save my comments for important topics. I do not just go and say on a blog, "hey nice article" and walk away. If I have nothing important to add to the information then I just do not comment.
Commenting blog only after judging its PR is not an intelligent idea I think. The blog where you find the post is interesting and you can write some comments in the form of your own opinion then just do that. So many blogs are there where you find interesting posts with lots of comments but low PR. So by posting comments with your username linking back to your site you can get noticed by so many other users. That can help you to generate traffic to your own blog/site.
Blog commenting is one of today's most effective off-page methods of increasing search engine rankings within a short span of time.so i would prefer old article with pr. it will give me two benefits
1 : one way link
2: pr juice.