I can claim to have tried them all. I switched from iPhone (since first iPhone in 2007) to a Samsung Galaxy S III earlier this year; then to a Galaxy S IV after my S III failed to float in the lake. Unless I see some major changes to Apple software (or their lawsuit manages to cripple Android devices) then I won't leave Android anytime soon. There was a learning curve to Android but I loved every minute of it since it had an answer to just about every headache Apple gave me.
I'm in the market for a tablet too, and am leaning towards one of the Samsung or Nexus tablets in the 7 to 8 inch range. I have a Nook color that I read and peruse magazines on, but its quirks are getting annoying, and any other function (apps, surfing the web, etc.) are a major PIA and disappointment once you've tried just about any other tablet out there. There are IPads out the yinyang in my house, as the kids and wife all have their own. I pick them up for a quick internet search from time to time, but don't use them a lot.
As for Windows - I currently have a Surface tablet. My wife bought it for work, but then upgraded to the Surface Pro. She loves it, but it's a work tablet, and she's not planning on dropping her iPad anytime soon. I tried to like the Surface, and used it for about 2 weeks. It has all the most popular apps I needed, so I wasn't missing anything I was used to on Apple or Android. I liked the idea of being a one-system man, and the Surface synced seamlessly with my work PC. I say synced, but it's like you can go from one to the other as long as you're on the Cloud. But, it was too heavy to be a bed-time reader, it isn't as "quick" to go from app to app as Android or Apple, and it it's lay-out was just too nutty for me. Windows 8 is like having a bunch of colored stickies all over your desk. I'll probably sell it on eBay soon.