According to your online business, especially in adsense whether to buy a new domain or buy domains that already had PR ?
it's better to buy new domain with no page rank and you develop it and make good seo you will get page rand 2 or 3 in 3 or 6 m
In my opinion, always old domains. But before buying an expired or aged domains please check with domain history, coz you never know maybe that domain was used to scam people.
If you change the niche for your "PR domain" you will loose it (PR) anyway. Apart, you seldomly know what has be done with the domain before. As Googlebots memory remembers "mistakes" for about 5 years, this might be an obstacle for your SEO efforts. I would always go with a new domain, exept I wish to keep the exact niche and know the exact domain history (SEO wise).
A new domain, always, for me. You really never know the past history of old domains and it can be risky commiting to a domain that has been used before (in a few instances they've been dragged through the mud). At least with a new domain you know what you're getting. Good luck with your choice.
If the old PR domain is clear and you are in the same niche, that's the best choice. If not, it is better to buy a new one.
only reason to buy a domain with PR would be if you want to capitalize on the site's existing PR. in other words, if you are a PR link seller. if you are wanting to develop a site, then it is better to get your own keyword rich domain, unless the one with PR is already kw rich
Search engine always prefer and old and reputed domain. I have have seen the page rank of my blog getting up gradually