I share Daannzzz opinion-
I prefer the Sierra Tower for its location and views -- BUT most (if not all) of the rooms are considered view rooms (of either DTD or the pool area), so unless you have booked a view room, you aren't likely to get a room here. I've always been happy with my rooms in the Sierra Tower.
Next, I prefer the Marina Tower. It's not as close to DL and DTD as the Sierra Tower, but it's close to the action. It's easy to pop down to the lobby, shops, or snack shops. You can sometimes get views of the fireworks in a standard room. The view rooms of the Neverland Pool are also fun (although nostalgic me misses the watching the ice skating rink at Christmas time that used to be in the Marina area before the Neverland Pool was constructed)
The Bonita Tower is my least favorite. I've never had a standard view room here, but I'd think the view is pretty boring. I've had a nice view room here (before they charged for them) which looked out over the falls and gardens, and still offered views of the fireworks. I've liked to room layout fine, but didn't like being farther away from everything.