While the quality and number of apps for the phones are pretty much tied, that's not the case for android tablets.
Android counts any app that runs on the tablet in their count for the tablets. This includes stretched out phone apps. The number of apps designed for the tablet that utilize the space etc. number so few as to be laughable. David Pogue, of NYT, tried to find out how many android tablet apps there were. There was no real way, because the google play store isn't like apple's app store; not all the apps for android are on the play store.
On the other hand, there are so many ipad-specific apps as to be almost ridiculous. It's really easy to d/l so many amazing apps, free or paid.

I don't know if this is an issue for the tablets, but you may have to hack the tablet (except the google brands) to install the latest os. I know the phones have this issue, where they have to wait for the carrier to push the latest os; with ipad, you d/l it when it's released.

Whether you get an android or ipad tablet, if you plan to do a lot of typing get a bluetooth keyboard. The touch screen is only meant to type minor items, like the search term in google or you tube. It isn't meant to type your report for work.

Good luck on your search.