The Hilton is the closest, follwed by the Buena Vista Palace. I've stayed at the Hilton, and would have no problem staying there again. It was quiet, clean, comfy, and we found service to be good.
The Hilton WDW (Can ometimes get a good rate on Priceline)
Buena Vista Palace (Formally Wyndam Palace)
Best Western DTD (The cheapest)
Hotel Royal Plaza (Newly Refurbed)
Doubletree Guest Suites
Grosvenor (Don't reccommend, also nicknamed the Gross-Venor)