I'm not sure.. There are tons out there that are good, so it really just matters with personal preference. I like Surpass Hosting (.com) because it's really cheap considering what they give you and their support is really good. They have both PHP4 and PHP5 so I would call them PHP friendly. Hey, look at that, they're also currently holding a Valetine's Day special from now till the 28th where you can get a full years hosting for only $1.
I'm not going to recommend anyone, but what you need to look for is someone who supports PHP4 and PHP5 and also supports mod_rewrite so you can have SEO-friendly URLs.
Most hosts support PHP, so you shouldn't have too many problems. Directories don't use many server resources, so any shared host should do.
Pair.com (not getting paid for referral) have hosted a large part of php.net and a mysql mirror for at least 6 years Some of their staff work on php and apache projects I'm not sure you can get a a more php friendly host