Link from the same theme website is better then different theme website. Because you will get irrelevant traffic from different theme based website which will not worth for your business.
I agree with you having link from related site no matter if its from PR 0 is always good rather than having a link from good PR site which is not relevant.As you are seeing various changes in google algorithm it will only affect your site and google hates spamming and irrelevant links.
Since link relevancy is the key, I would suggest getting links from relevant sites even if the page rank is zero…
[FONT=Verdana]We seem to have an unusual level of agreement on this subject, so I don’t think there’s anything left to say.
Thanks to all who contributed.[/FONT]