Is it better to have back links from multiple sites?

yes.. google always check backlinks.. but try to get form good relevant sites

 

Thats exactly my point, google views banners as advertising (paid) and doesn't credit them as much as organic links.

 

So here is the next level... How do make an equation then?

300 PR3 backlinks from ONE HIGHLY REPUTED SITE = 50 PR3 backlinks from 50 different websites?

Please use your experience to make an equation...

 

It would be almost impossible to come up with a reliable algorithm (unless you work for google ). There are a lot of factors to take into account, like the amount of outbound links on the page, and the degree of relevancy that google decides the page has.

 

what if we assume that all other parameters (relevancy and outbound links) are same on both side of equation ...

it should be just a guess based on experience, not a real time formula...

 

It is advisable that a) links come from different sites (links from one single site might be filtered out), b) links come from sites with DIFFERENT PR (do not neglect PR0 and PR1 sites, that look unnatural and c) links should have different anchor texts (again, if all are the same search engines will detect that).

 

we call it domain links. the more links you have from different domains the better it is than getting all your links from one domain with many pages.

 

First of all, just because the home page has PR3 does not mean that the other pages on the site are PR3. 300 site-wide links is not the same as having a single inbound link from 300 sites. Site-wide links are likely discounted or devalued a bit. Google can easily detect that they are part of the page template and not contextual links. Even if they did not discount site-wide links, Google is likely looking at not only the number and quality of inbound links to your URL, the link text being used to link to your URL, the relevance of the pages linking to your URL, but also things like the number of domains that link to you.