I rode RRR once and don't care to again--not because of the scare factor (though it did take me a bit to work up the nerve, despite being a coaster lover!), but because, like others have experienced, it gave me a headache. I just don't think it's a well-designed coaster; there's a lot of speed but not a lot of moments of weightlessness and it's not a great combo. It's also lower capacity than many other rides, and when I went on it in 2015 the crew running it were very slow and inefficient, so the line takes forever.
I'd still recommend to do it the one time just to experience it. I just wouldn't tell you to expect to love it.
The Hulk coaster, though? Love it, and agree with the earlier assessment that there's less psychological buildup since it launches you when you're only halfway up the "lift" hill. I'd say if you can ride RnR, you can ride the Hulk coaster. I think it has better thrills since you can actually see where you're going, but there's not a big psych-out moment at the start; you just go straight into the fun part.
Finally, Doctor Doom's Fearfall is a ride I actually really like because I find it much,
much less frightening than an ordinary open-air drop tower. Every time I ride one of those things, there's the slow buildup as it hauls you to the top, the sickening moment where you hang there, waiting to drop--I
like some drop rides (ToT is a favorite), but the psychological buildup on the open air style of drop tower is too much for me. Every single time I ride one I experience intense regret as it nears the top of the tower. Since Fear Fall is actually a
launch ride, not a drop ride, you get none of that--they build up a little anticipation with a countdown, but it's absolutely nowhere near as scary as it looks. Registers completely differently in my brain and I can actually enjoy the launch and fall sequence instead of hating the anticipation. It's kind of a silly ride, but I really enjoy it.