Let's say this -
I get 5 links from PR1 or 2 niche/related sites/pages that have their own strong backlinks, say 1000 strong backlinks and decent rankings if not top 10 or 20.
I get 10 links from so called PR5 sites/pages that have hardly 3-4 backlinks and no rankings but a high PR.
I will prefer those 5 links. PR doesn't matter much. It will go high after a site's backlink strength. It's better to get related links from sites that have their own strong backlinking... and PR doesn't matter much there. If you get a good PR too, it's all great.