Which of these packs add the most gameplay?

I think Backyard has the most game play options out of the choices listed. I like the new drinks and the slip n slide is fun, especially when you add soap. You do need some lawn space for it though, but I think paired with Seasons it's great. There is also a bird feeder but I wish it had some more interactions (there may be a mod for that).

There's a guide that describes everything in detail about the SP on SimsVIP if you are still on the fence about which pack to buy.