As mentioned there are differences between the hotels: themes, room sizes, pools, on-site restaurants, club lounges, etc. The answer to your question is more of a personal answer, it depends.
How many will be staying in the room? As noted in one of the above posts, the room size differences are actually pretty striking. If there are 5 of you staying in a room, PBR's extra space may well be worth much more than $55. If there are only 2 of you, then room size may not be a big issue to you. Also, are you looking at base, view, deluxe or club rooms at each of the hotels? The club lounges are a bit different for each of the hotels as well. So if you are looking at those, you might want to check out the reviews of each hotel's club lounge.
For me personally, while RPR is closer to IOA and HRH is closer to US, all 3 are close enough (and with the water taxis) that distance to the parks is one of the least of my concerns. When my kids were younger, RPR was their favorite hotel as they liked the interactive pirate ship area of the pool. But now, they like PBR the best as the rooms are larger and they like to choose between the quieter/adult pool and the larger main pool with a slide.