I like to look at backlinks, equal to money! Woohoo, green hard cash money!
When a .edu, .gov, or even a high authority .any site links to your page or site within the first few paragraphs of a killer, well authored article, that's highly relevant to you and the visitors... cha-ching, that's a buck, and equals "1" full-credit-backlink!
On the other hand... when you can get a blog comment or directory link that any other 3-p (#*$!, pills, poker link [en.wikipedia.org]]) can just as easily get, well... that's .01 penny, and you would need 100 of these to equal "1" full-credit-backlink!
EVERY other backlink falls somewhere in the middle of that chain to me, and I try to stay as close to $1 as often as I can.
IMHO... blog comments, even on VERY relevant blogs, are only worth a penny or two at most in backlink value, nofollowed or not!
Just my .02 cents...