I voted skill based, mainly because I hate fighters that can only fight, or mages that can only blast, or clerics that can only heal. If I play a spellcaster, I'd rather be using illusions and charms to get the most bang for my buck, rather than just getting a fireball-style bang.
Generally I am happiest when I have bucketloads of skill points that I can rely on without having to worry about running out of daily uses, or to supplement my fighting skills. As such, my warriors tend to be swashbucklers, fighter/rogues, rangers, or even 4 sp/level barbarians! My spellcasters are usually sorcerers with a decent enough intelligence (plus being human) to get some good cross class skills.
Honestly, my new favorite class is going to be the scout once I get a chance to play it in game.