None, now.
The last clever daily strip was Boondocks and it ended way too early.
Far Side and Calvin and Hobbes were great. Both over now. Doonesbury used to be good 10 or 15 years ago, but kinda sucks now. Get Fuzzy is okay, but it's also not as good as it used to be.
But the vast majority of daily strips are amazing in just how terrible they are. They're not funny, not clever and most are stale re-runs of the same awful gags that have run for decades. Print is a dying media because they don't get it. Look at most popular web-comics, like The Oatmeal, Cyanide & Happiness, Penny Arcade and Perry Bible Fellowship (maybe that one ended). Most of the time they're hilarious. And yet nothing even approaching their caliber ever appears in newspapers, because the senile idiots in charge would rather pump out the same tired Marmaduke and Family Circus crap no one reads. The funnies could be overhauled over night, but instead they'll die a slow death with the medium that carries them.