I have heard it bandied on the internets about that old schoolers are considered to be against skill systems. Personally, I am not against skill systems. I don't care for skill systems in D&D, but in other RPGs I have no objection to them. My bigger problem with skill systems is that so many of them are cumbersome and/or just plain boring. For my tastes Traveller and RuneQuest said 90% of what needs to be said about skill systems. Which is good, I guess, since so many games rip off RQ.
That's vaguely acceptable if you're Chaosium, but what is everybody else's excuse? A list of skills and a die mechanic does not a good skill system make. I'll grant Savage Worlds some points for brevity and Clash Bowley's In Harm's Way for allowing different skills to solve the same task, but most similar systems don't do much for me. Lords of Creation has a neat mechanic where each new skill level gives you better chances of success and broader uses for your skill. I like that a lot.
And then there's the make-your-own skills games, like Unknown Armies, Ghostbusters and Risus. I like the concept, but I would have trouble keeping it straight for a serious game. I've never played UA but if I did my charsheet would probably say stupid things like "Han shot first" and "I'm Harley Race and you're the new babyface who thinks he's hot stuff".
What other skill systems do people like?