From absolute best to wonderful:

Issue 227 by Stern and Buscema, "The Murder of Doctor Banner!" Doc Samson psychoanalyzes the Hulk.

Issues 235-237 by Stern and Buscema, the three-issue rumble with Machine Man.

Issues 239-242 by Stern and Buscema, the revelation of "They" and why they've been after the Hulk, and the mind behind it all. Plus the Gold Bug action!

Issue 250, by Mantlo and Buscema, the Surfer tries to use the Hulk's power to shatter the invisible barrier around Earth.

Issues 364-367, "Countdown" by David and a dude named Jeff Purves, and Keown shows up. The Hulk is poisoned by one of his enemies. During the course of his "investigation", the Hulk fights the Abomination, the FF (minus Ben, with She-Hulk in there, ugh), the Leader and others.

Issues 299-300, by Mantlo and Buscema and Taloac, the mindless Hulk becomes a threat that cannot be stopped, including one of the premier fights between Thor and the Hulk (I'm sure it has even more impact having read a year's worth of Hulk with Bruce Banner's brain stories up to then).

Not to sleep on the Len Wein/Sal Buscema stuff, because that's where my first Hulk issues came from.

I was wondering, if you all had to pick one issue, either in the Hulk's own title or other mags, as your favorite Hulk story, what would it be?

This is my favorite Hulk comic, I believe:

Kirby version of the Hulk, in this issue, with the Hulk in full "thug" mode, plus the intro of whom I'd say was the Hulk's true mortal enemy, Tyrannus (it's the duality/mirror thing, with the "Monster" exterior of the Hulk and the "Beautiful" Tyrannus who is so much more a monster than the Hulk ever could be. Great artwork, and for some reason the Hulk's love for Betty really comes through, as he endures prisoner degradation to keep her safe.

This is one of my top 5 favorites, I'd have to really think about to pick my all-time favorite.