To expand on me for the big 3:
3 - MMM. Has the best pool! Location is good for Funko Fundays, Video Game stuff, and panel pickups. Beyond that it always felt like a munch longer walk for me. Personal run ins there, Will Wheaton at the bar and Cladio Sanchez in the pool.
2 - HBF. Best Views. Location is great for Hall H & Ballroom, FX area, Stadium events and the convention hall in general. Probably my favorite room if you have3+ people in your group for size. Personal run ins there, just Dan Harmon.
1 - Hard Rock. Best Atmosphere. Great location for off sites and very easy access to the show floor. Its across the train tracks....but just barely, easy walk everywhere. Rooms are really small for bigger groups....but they are the nicest quality to me. Personal run ins there: Walking Dead cast, Suicide Squad cast, Deadpool cast, Jason Mamoa, Ezra Miller, Chadwick Bossman, Harrison Ford.....and so many more. Bonus points as many big parties are in the hotel and depending on what floor your room is on...you may be able to walk right in to some.