Yacht & Beach Club really are tops in theming and amenities. It's an easy walk to Epcot from both resorts, but the Beach Club is closer. It's a longer walk to MGM but still manageable. However, if you don't feel like walking, you can take a boat to both parks.
Y&B have arguably the best pool on property. Stormalong Bay is really a mini waterpark. They have a "lazy river" complete with inner tubes, a sandbottomed shallow pool and an active pool. There is also a huge waterslide set in a shipwreck.
Also, IMO, Y&B have some of the best restaurants on property. Beach has Cape May Cafe, which has a great character breakfast every morning and a fun clam bake every night. Even if you don't like seafood, they have landlubber food and a great dessert bar. Over at the Yacht, there's Yacht Club Galley, which has a great breakfast without the characters and is a great spot for a casual but delicious lunch or dinner. And of course there's Yachtsman Steakhouse, which is a real treat. It's my favorite restaurant on property or off. In between the two hotels is Beaches n Cream, which serves fabulous ice cream and diner-type food. And if you feel like getting out, the Boardwalk and its restaurants and entertainment are a quick walk or boat ride away.
Y&B are smaller resorts. They only have about 300 rooms each, if I remember correctly. They are very popular and tend to sell out very fast. I prefer the Beach over the Yacht because of its more relaxed feel, but they're both great.
For pictures check out this link:
http://allearsnet.com/acc/g_bc.htm
http://allearsnet.com/acc/g_yc.htm