I've always been a fan of either WIX (who make many of the premium filters out there, as well as a good portion of the OE filters), or the Purolator Pure 1. For some interesting reading on the subject, check out theis page:
http://www.scuderiaciriani.com/rx7/oil_filter_study/
This guy cut open a large aray of filters from many manufacturers and the general consensus is that NEARLY all filters are either made by Champion, Allied Signal, or WIX (mostly Champion), but there are a lot of minor enhancements to each line that can make a big difference (Anti-drainback valves, etc.).
Another good site for everyone to check out is filter1.com
These guys sell WIX filters at serious wholsale discounts with free shipping if you buy at least six filters (don't all have to be the same part #). You can get a WIX filter for about $3 which would have cost $6-7 at your local NAPA or CARQUEST (WIX makes both of their house brands. Anyhow I'm sure that's more than anyone wanted to know about filters, but I thought it was interesting to learn about.
-Nate