If you really need flash and intent to use it for learning, I would recommend forgetting about using a tablet, and rather buy a light laptop such as HP Probook 430 or a asus vivo book x202e/s200 if you want to have a touchscreen (
Best ultrabooks under $800 (or $1000) - top 8 cheap ultrabooks in 2013). Even new they are relatively cheap, but it shall be possible finding some second hand in a small tablet price range. And these will last you longer than 2 years for sure.
If you really want to close the choice between the two options you mentioned, and forget about Thorstein considering tablets a fade, I can only say without any excitment the windows RT, which is maintained by msft at least and has office. But you may still encounter some issues on some flash web site even when it enabled with 8.1 (so you might want sticking to 8.0 until close to the end of the free 8.1 period, cf
After 8.1 upgrade, Adobe Flash does not work in IE - Microsoft Community). And I don't see much interest from the developers to support it...
PS: I have a surface RT, a google nexus 2012, an ipad mini and a playbook, and a HP Probook 430 ... (plus some desktops).