opinions on my link idea

Getting my head round best backlinks etc. But just want to check a couple of things over and get some opinions.

How would you rate the following backlinks, lets say they are all the same pr, niche, do follow etc.

1. Blog coment with backlink
2. Blog roller backlink
3. An actual backlink on the web page i.e in the blog/main content itself
4. Forum post with backlink in the post
5. Forum profile signature with lots of posts
6. 1 post but with profile signature.

Also I have a main website to promote. What would you say about creating various blog sites about themes from the website and then linking to the main site, thus giving me bloggs to promote and increase pr on to strenghten the links to the main site. If you think this is a good idea what blogger is strongest to use. I am think wp with do follow plugin

Probably number 3 but there are many other variables to consider, OBL's being a very important one.

OBL's in terms of the main site or the blogs, and how would they effect as a variable as I would obviously keep the obl's on all sites to a minimum.

Higher OBL's mean lesser link juice. You need to keep that in mind.