I believe The Beatles: Rock Band came the closest to being perfect. Eveything about that game was just beautifully done and the only things missing was Pro Drums, an option for Keys, and a few more Beatle songs (Hey Jude, Strawberry Fields Forever, Yesterday etc. etc.)
As someone who’s worked on mods for Stardew Valley, you can tell that CA put a lot of effort into making the game. It’s honestly impressive how much he was able to do.
That being said, the game’s code is far from perfect (although it’s been getting better over time). It just somehow came together to make an amazing game. He’s also been pretty receptive to feedback from modders, which I think has drastically improved the code over time.