I voted for Grandpa's Grove, but it's closely tied with the Al Fresco street market. The tractor from Grandpa's Grove is extremely helpful for sims with large gardens and is fun to watch; the fruit and vegetable stands from Al Fresco are useful if you want your sims to have the chance to buy fruit they wouldn't be able to buy at the grocery store (like the special grapes found only in France) and using buydebug feels too easy. It's fun to visit the stands every day and check what is on offer.
The Last Venue of Amore is stunningly beautiful, probably the most beautiful store venue, but it's so densely built I found that it makes my graphics render more slowly.
