Link to index (PR5) or the forum (PR6)

I need a clear answer to have the best SERP in this case.
I have most of the links link to the index page. DMOZ also links to the index page.

BUT…a PR 6 website links to my forum page and thanks to that website (backlinks over 100+), my forum has a PR of 6 while the index has a 5.

In addition, most SERP in Google provides link back to the forum pages and not the index page. But if I type the main keyword, it provides the index page on Google

[b]So, should I change all my links from index page to the forum?[/b]

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