plc90210 - 2:53 am on Sep 14, 2012 (gmt 0)
1. Relevancy - Believe me, YES. If you don't believe me, look at this: [youtube.com...] (listen to the part starting at about 0:45 in the video).
2. Domain Age - not important
3. Google PR - extremely important
4. IP Location - not very important
5. Quality of Content - fairly important; I would imagine links from sites that scrape content probably aren't considered very valuable.
6. User Experience - not important at all in terms of how much link juice the link will pass; important in terms of how much traffic you could get from the link
7. No of daily visits - See #6
8. No of OBLs from the page where I get a link from - extremely important
9. Not important
I was recently doing backlink analysis on a PR4 site that was ranking in the top 5 for a keyword full of PR7 sites on the first page. The secret? Highly relevant links with really low OBL. The PR of the links wasn't that high (highest was PR6, most were PR2-3). There were a few backlinks which not only had high PR (4-5), but also had really low OBL (< 10). They pages were also highly relevant. I imagine these links are the main reason the site is ranking. Things like the page title, text on the page, text around the link, H1 tags, etc are extremely important in helping to determine the relevance of a backlink.
Bottom line: #1, #3, and #8 are extremely important, the rest - not so much.