I just bought a couple of Raspberry Pis and I get the same exciting this-is-the-start-of-something-really-cool vibe from them as I did from my first Apple II back in 1980.
I've used Mint since then; never looked back. Mint on an old X220 thinkpad is better than anything mac has done since then. Requires a bit of overhead on setup to get power management right, but I paid that price years ago and can endlessly clone HD images.
Bonus is, most of my work product ends up on the EC2 anyway.
I feel like the only thing we've actually lost was the requirement to use iTunes to set up a new iDevice, and good riddance to that. An iPod really was a peripheral whereas their modern successors are fully-fledged mobile computers.
If you mean use an iPad as an external display, that's a rather niche use. Is there a reason that the 3rd party app Duet Display doesn't meet your needs?
Google, Apple, and Microsoft, though, seem pretty safe.