Yeh I honestly think driving a Ferrari has practically no allure to Hamilton, unless it's the dominant or most competitive car.
He was groomed by McLaren from a young age though, so obviously that was always going to be where he ended up. Being a Ferrari driver also means being in the spotlight; involved in marketing, press events etc. All teams do, but the big teams have a lot of that 'image' to live up to. I think if Hamilton took anything from McLaren, it's that he no longer wants any of that. The fans are rabid, the expectations and the pressure to perform would be incessant and I'm sure all consuming.
He just looks so much happier at Merc, I believe he even said one of the things he liked about Merc was getting away from the marketing and events behind the scenes McLaren had to put on. He just seems to be able to do his own thing more at Merc. It obviously helps that since 2014 the Merc has been the car to drive, but even in 2013 when they were fast but race pace was really lacking, he didn't seem frustrated or burdened. He comes in, does what he needs to do, focus on what he needs to focus on, then he pisses off for a spell over in the states, does his music stuff, goes and just generally chills and has fun, does all the things #blessed peoples do, then turn back up to work all fresh.
I'm a Hamilton fan, I enjoyed his style of racing the moment he got in a McLaren in 2007 and like many I wondered wtf he was thinking going from a team that has historically either won a championship or contended for it to a team that had potential but nothing to really show for it. But I think going to Merc was the best thing he could have done, getting away from McLaren and giving him some breathing room and a fresh perspective seemed to really help him out and I would argue that Niki Lauda has been a huge influence in getting his head sorted. Hamilton no doubt always had speed but he also seemed to come in and out of focus, get flustered, do stupid shit etc. Since Lauda came in with his no bullshit tell it how it is approach to getting his head sorted, I reckon Lauda turned Hamilton from a guy with a lot of speed and potential into the more well rounded driver he is right now. Hamilton still has his moments but an emotional guy like Hamilton needed someone like Lauda to give him a 'you're good, but if you want to be the best, you're going to shut up and listen to me' approach.