PostgreSQL or MySQL (or something else)?

I'm writing a web application in Perl. Database Architecture is top of my planning list and would like /prog/'s opinions. The web application is an file upload host (LOL ORIGINALITY). But seriously, it won't be a general one like Rapidshare, it'll have a very specific target audience.

Anyway, I have seen /prog/ reccomend PostgreSQL numerous times with no reason other than "better than MySQL", though to be honest, MySQL seems like a daftly compacted pile of crap aimed squarely at the CONTENT MANAGEMENT SYSTEM and PHP ENTERPRISE FORUM market.

So I ask you, /prog/, which database engine should I use and why??