The closest thing with a beach is the Beach Club Villas. Stormalong Bay is the main pool and has a sand bottom at one section of the pool.
Here'a a link to www.allearsnet.com web site pics of the pool http://allearsnet.com/acc/g_sab.htm
If by 'beach' you mean a lakefront sandy area with lounge chairs, then VWL and BCV.
If you mean the above, plus being able to swim in said lake, then none.
Well, although technically there is a beach on the side you go out to Epcot (Samantha Brown "checked it out" on her TC show), you can't swim in the water from there. There's sand and beach loungers though.