I haven't had a chance to ride Rise of the Resistance all the way thru yet, so my vote goes to Millennium Falcon, which I ride repeatedly every time I go to HS.
Runaway Railway is excellent, and I love it, but it's second to MF.
The funny thing is- HS was one of my least favorite parks for so long, I don't think I went there at all last year. IMO, they had two decent rides, Tower and RRC, and it often seemed too long a walk to just do those two and leave.
BUT NOW- I spend hours Play-ing in GE, ride MF repeatedly, yearn for the times I get a FP to MRR, and Tower and RRC are still there as a bonus. (although I've yet to find a decent restaurant where you don't pay thru the nose). I might even say HS has gone up to my Top spot for Parks.