Each resort is different but great. They all have great theming, service and locations.
RPR- is the least expensive of the three, but truly at a deluxe level. It is supposed to be similar to the moderate resorts at Disney, but I actually think it offers more.
HRH- is the next tier. Very cool atmosphere. The staff though is the least customer service oriented than the other two resorts based on reviews from different people. But its a very nice resort.
Portofino- Is wonderful. Romantic and you feel like you really are in Italy and it's family friendly. It's supposed to compete with the Grand Floridian at Disney. It is their top resort at Universal and the most expensive of the three.
I think you would enjoy any of them. They are all close to the parks and I have stayed at RPR and Portofino. I am going to try HRH next.
Hope that helps!