Tablets are harder to pick then a normal PC.
First you have to figure out the size you want 7-8 inch one, or a 10in one. 10 in is better for most things but is bigger and usually you don't carrier it around much.
You then need to figure out which direction you want to go.
Apple with an ipad (cost a little more, but really does get the most apps)
Google/Android/Kindle. A little cheaper.
Windows… Still getting there.
First things first. Tablets are not made for typing much more than a basic e-mail. Anything more than that you should buy a keyboard. Just know that going in.
For Android tablets are nice, I just wish they made better ones. Don't get me wrong, Sony, Samsung have good tablets. But they just seem to be missing something. The Kindle tablets, even though they are Android, they pretty much have an amazon skin on top. They are nice, but everything goes through Amazon. (where as other Android tablets aren't that way).
Windows Surface tablets are nice and come with a Keyboard cover. But you have realize this is still a tablet, and not a full version of windows.
Most windows tablets should let you do most of what you need, they are behind in the apps, but its still a good value.