... This was the WRONG question to ask. *looks over his list, over 50 long* I have... quite a few, to say the least.
The absolute best has already been mentioned, in the first post; The Order of the Stick. Best. Webcomic. Ever.
Runners up: PvP Online; a decade old, newspaper-like comic strip, only it's actually funny. Has definitely improved a LOT over the past month, had been getting kind of stale, before that. http://www.pvponline.com/
Something Positive: The adventures of a man with awful luck, an extremely sarcastic attitude, and a huge cast of equally fucked-up people. Very wordy, very dark humor. Occasionally NSFW. http://www.somethingpositive.net/
Penny Arcade: The classic 'two guys on a couch discussing video games', this is the stereotype that set the genre. Excellent art, excellent commentary on the gaming community, and often brilliant writing. Language NSFW. http://www.penny-arcade.com/
XKCD: A surprisingly innovative comic, written by a genius of a man, who knows nerds better than nerds do. Despite its simplistic, stick-figure drawings, they're very poignant, especially his art pages, and the words are superb. One of my favorites. http://xkcd.com/
Gone With the Blastwave: A unique idea; a futuristic world, resembling a FPS, as if it were real life. Excellent art, above-average dialog, and just simply humorous. Unfortunately, extremely, and I mean extremely slow updates. Next *page* is planned for 2009. ;_; http://www.blastwavecomic.com/index.php
Three Panel Soul: Sequel and successor to the college and gaming themed comic, Mac Hall (http://www.machall.com/
), a light-hearted look at random thoughts on life, the universe, and everything, in three panels. http://www.threepanelsoul.com/index.php
Online gaming related: Dark Legacy Comics (http://www.darklegacycomics.com/index.html
) and Hammer of Grammar (http://meghanohara.org/wordpress/
) are both well-written, World of Warcraft related comics, although the latter, sadly, seems to have stopped updating... though it's still quite funny, even if you don't play WoW. The Noob (http://www.thenoobcomic.com/index.html
) is a more general look at online gaming, mocking mostly older games, like Everquest and Ultima Online, or MUDs, rather than the newer generations... though still completely relevant.
And that's the short
list. I could easily go on, giving a review of every comic on this damn list, but these, aside from the ones mentioned, like Goblins, 8-bit Theatre and Order of the Stick, are the best of the crop.