I am going to Bard on the Beach, which Shakespeare play should I see and why?

If you're leaning toward a comedy, you've got two to choose from -- not just "All's Well That Ends Well," but also "The Comedy of Errors." Of those two, "All's Well" is probably done less frequently (and it's probably staged less often than "Othello"), which might be a reason to choose it. The great tragedies are done a lot, and "Errors" is a pretty popular comedy. It may not be staged as often as "A Midsummer Night's Dream," "Twelfth Night," and "As You Like It," but I'd guess that you'll get more chances to see it than you will to see "All's Well." Whichever show you choose, you're probably in for a memorable theatre experience.