Hilton is more of a resort but you will be pretty isolated and limited to overpriced (and imo crappy) hotel food - there isnt much within walking distance.
Sheraton is much more central with lots of food and things to do nearby but it's a city hotel on the beach.
Sheraton rooms are smaller but more of them face the water.
i would suggest sheraton to take advantage of waikiki, if you want a resort go to another island instead of going to hilton