Looks like most of us here have similar tastes.
My favorites on paper, most-liked highest:
Zits (Zits | King Features Syndicate : King Features Syndicate) - Almost always just plain funny.
Foxtrot - It’s all about the characters.
Non Sequitur - Like The Far Side was, but better.
For Better or For Worse - My first “continuity” comic, and still IMHO the best.
[slight hijack] Are the Peanuts strips running now reruns or stuff done by a successor? And if they are reruns, when are they from? [/hijack]
With online comics I tend to start reading one in the midst of procrastination, finish the archives, and just add it to my daily list not because I like it or because it’s good, but because I want to keep up with the freakin’ story. There are a few that I actually enjoy, though:
Absurd Notions (http://www.cerulean.st/absurdnotions/) is well-written, well-drawn, and is always interesting, a very rare combination. Too bad it’s only three times a week.
Sluggy Freelance (sluggy.com): If you must read only one webcomic, it should be this one. It’s also probably vying with User Friendly for most widespread.
Road Waffles (.com): The kind of stuff that’s never going to be in typical mass-media. Stuff that you know you really shouldn’t find funny, but do anyway.
Nukees (.com) is generally just above-average, but has the occassional gems that make me feel that reading it regularly is worth it.
Ozy and Millie (.org) deserves mention. It’s wacky, and is the best-drawn webcomic I’ve seen, and the writing is good to boot.
So there’s a to-do list for anyone with a good connection for that next term paper or whatever. 
Have fun.