Royal Pacific is usually where families with younger children stay because it has the calmer family pool, Hard Rock is popular with teens and 20-somethings because of the rock theme with the music piped in everywhere even underwater. Royal Pacific and Hard Rock are also the two to decide between if you want the shorter walk to either Islands of Adventure (Royal Pacific) or Universal Studios (Hard Rock). Portofino is the fancier hotel with an amazing lobby but much longer walk to the parks (however you can take the boats as long as it isn't lightning out).
They are all amazing, so it really comes down to which detail means more to you. I will say though, that if Portofino is more I would go with Hard Rock over Portofino. One isn't worth more than other they are pretty equal in terms of quality.
For you (20's, no kids as you said) I feel it comes down to Hard Rock and Portofino. So let's compare:
Food: PORTOFINO - Portofino doesn't even have contention when it comes to food. Hard Rock does not have awful options, it just simply can't compare to the far more numerous, far higher quality options at Portofino.
Atmosphere: PORTOFINO - As I write this, I'm starting to get the feeling Portofino's going to win. Hard Rock Hotel is far more like a typical hotel (it is unique, but not quite so much as Portofino) whereas Portofino literally transports you to the beautiful riviera of Portofino, Italy.
Okay, I would go on, but there is really only one area Hard Rock has a slighter edge on Portofino: Accessability. And even then, the only edge it truly has is being located closer to the parks and Citywalk geographically. Portofino still offers beautiful paths to walk to the resorts, as well as bike taxi and of course water taxi.
My vote (or best suggestion) is for Portofino. Truly an experience you will never forget!
Due to the slight difference in price, we tend to stay at Portofino when we feel like splurging and RPR for all our regular visits. Portofino has slightly larger rooms and definitely larger bathrooms. The theme is lovely and the ambiance is wonderful. But, honestly, I think I actually prefer RPR. The south Pacific theme is so relaxing, the lobby and fountain area is large and pleasant to hang out in, and the area outside Jake's bar near the waterfall is a fantastic place to sit and relax with a drink during the evening after a long day at the parks. Plus, when you feel like taking the boat instead of walking, RPR has the best, most shaded place to wait for it.
So, if it were me, I'd pick RPR.... but be sure to use the $30/night you save to have dinner over at Mama Della's at Portofino!!!!
I have stayed at all three, but Hard Rock gets my vote. Keep in mind it is a couple minute walk to the Universl gate / CityWalk and a few minutes more to IOA.
If the water taxis aren't running, be prepared for a hike from Portofino if you have to walk. Royal Pacific ins't as bad but it is easily ten minutes by walking path.
We stayed at Hard Rock last year and are going back again this year in June. We never took a water taxi once because it is faster to walk. The place is hoppng at night around the pool and people seem to be more social than at the other two hotels.
All three are first class and super clean, so you can't make a bad decision. If you look at the entire resort on Google Earth, you will see how close each one is to the parks and CityWalk.
I had a chance to dine at the palm last october and it was great (exspensive though)! Best steakhouse in the South is Berns in Tampa IMOP!
Walt Disney World's Magic Kingdom
Disney's Animal Kingdom
Disney's Hollywood Studios
Disney California Adventure
Universal's Islands of Adventure
Universal Studios Florida
Universal Studios Hollywood