I can't give you any help regarding Forbidden Journey, because I haven't been on it yet....but as for Hulk and Mummy:
I almost never discourage someone from trying a new ride. How else do we know what we will love? However, Hulk is one of the few rollercoasters I don't really have any desire to ride again (and I LOVE roller coasters!). It's not the fast take-off that bothers me (that is my favorite part of RnRC), but the roller coaster is very big in a rather tight place. The G's that come from making some of the tight turns left me with a pretty annoying headache. I didn't have that problem with any other rides at Universal, never had it at Disney, and never at Busch Gardens either. Just with Hulk. Maybe it was just a random thing that wouldn't be an issue again, but there are too many other rides for me to worry about the headache I might get on Hulk.
Mummy: LOVE IT! This ride is super fun! If you can do any of the Disney coasters, you can handle Mummy. To me it doesn't seem so much like a roller coaster as it does a fast "dark ride." It goes fast and then slow and then fast, etc, so you can keep up with the story. It is pretty scary as far as the story, but you never sit in front of anything for too long so it doesn't really start to get to you in a panic - I can't escape! - kind of way. I definitely recommend this one!!
Enjoy your trip and good luck on new rides!!