The point of Ultimate Hulk (or any Ultimate character) is to be different than the original. Some people miss the point and automatically lash out against it.
Personally I think Ultimate Hulk rocks, and if you dig him you check out the Ultimates vol. 1 HC. If after that you are hooked on Ultimates, you should wait for the Ultimates2 HC, or get the trades or something.
As for my favorite character of all time, 616 Hulk, I would check out some of the following (depending on what writing style you like better):
Essential Hulk vol 1. The classic Stan Lee stories!
Hulk visionaries: PAD vol 1-3. The Hulk turns gray. There are tons of great stories by PAD. He wrote the book for over 10 years, and is one of the best Hulk writers of all time.
Future: Imperfect. Hulk fights an evil, possible future version of himself. The Maestro! Considered by many to be one of the best Hulk stories EVER (written by PAD).
The Incredible Hulk HCs vol. 1-2. These were written by Bruce Jones, and got a lot of new fans into the Hulk. Some people hated Jones' run, but I liked it. Personal taste will determine whether to get it or not. It has an X-Files feel to it, and is pretty cool.
Just a few suggestions.
