Beach Club, without a doubt. For the pool area and the proximity to Epcot. To be able to get it for the same price as Saratoga Springs is a bargain too.
Ssr is a favourite of ours but this year as a special treat we stayed at the beach club. Beach club wins. It's so much more relaxing, strolling to Epcot on a evening or around to the boardwalk.
Beach Club. Location and amenities beat Saratogo Springs hands down. If SS is a villa then the accommodation there is definitely better but I think with your oldest only 13 I'd still go with the Beach Club.