Seeking tablet advice for my father...

My dad would like to get a tablet. Our budge is $100.00 - $500.00, with an emphasis on the $200.00 - $400.00 range. My dad is getting older, so he needs something easy to use, with good options for adjusting the size of things or zooming in. He would like something that has good performance. As an experienced computer user I'm adding that it should be a little future proofed. So here are the minimum specs we are considering:

1. Quad core processor
2. 1 gig RAM
3. 16 gig memory
4. Expandability
5. 1280x800
6. Good wireless strength
7. 9" screen
8. Newer builds of the OS, such as Android 4.0 rather than 3.0
9. Good build quality and good quality overall

My dad will mostly be using this to browse the web, check email, maybe look at newspapers, magazines or books. He may watch movies or videos on it. I think he should also have a good office program with a spreadsheet built in so he can journal and keep track of finances.

We spent a few hours at NewEgg tonight and he liked the looks of the Asus 700T Transformer 10.1" He is also interested in upping the budget for a Windows 8 tablet. But he's hesitant about this. So I had a brilliant idea. I thought I could here and ask the experts here! Here are my questions:

Are the more expensive Windows 8 tablets worth the extra $100.00 or so?
What is the best OS for him? Android, Windows 8, something else?
Considering what I have said here, what tablet would you recommend for him? Why?

I really appreciate your help on this!

Have you considered an iPad 4?

I'd probably match whatever his phone is. That is, assuming he uses a smart phone. That way, he'll have essentially the same apps available and navigate the same way. I wouldn't get hung up on a quad core processor. There are dual cores that are faster than some quad cores. It's pretty hard to get a "bad" tablet in the price range you are talking about. I think all tablets have accessibility features to make reading easier/larger.

I find iPads/iPhones extremely annoying/limiting due to how you move around the OS, so I bought a Nexus 10 for me. However, my wife and kids use iPhones, so they like iPads. BTW, I use a Windows Phone due mostly to the integration with xBox music.

Windows 8 is ok as long as he's not planning on using lots of phone/tablet apps. The Windows 8 store is pretty anemic in comparison to what you get with iOS or Android. However, you do have the option of using Microsoft Office or other Windows Apps if needed. Surface RT comes with Office, but isn't a typical Windows system and is very thick compared to a typical iPad or Android device.

OK, thank you for your replies!