You forgot to mention, for what purpose you need the tab. If you need it for everything except graphic intense gaming, watching movies in 16:9 and showing off top notch specs, the Tab A is probably the device to go.
I dropped my Tab Pro 10.1 Wifi (which was in use for more than a year) on the floor a few days ago and am now running with the Tab A 9.7. My main use is reading epub and pdf, browsing with firefox, doing email and occasionally working on office documents and playing a match of chess, sudoku and the likes.
In my opinion the Tab A is a perfect device for these purposes. All such tasks are mastered with energy saving mode activated in an extremely smooth way, actually much smoother than the Tab Pro 10.1 Wifi with the Exynos cpu. Especially Firefox lagged a lot on my Tab Pro when scrolling web pages, rendering text and zooming the page. The Tab A 9.7 behaves just buttery smooth doing all these tasks.
Another advantage over the Tab Pro might be, that Samsung in the meantime actually has decluttered its user interface a lot and even allows certain preinstalled apps to be removed from the device (like it is the case with the Lumias).
Samsung confirmed that the new Android M will be rolled out on the Tab A (which is on Lollipop already) by the and of this year whereas for the Tab Pro Lollipop is still pending.
Concerning display resolution: With my reading specs on I have no problem reading stuff. Most of us still use Notebooks with a lower resolution, so we are inured to screen resolutions of 1366x768 on a 16 inch display. 1024 on a 10 inch display shouldn't be much of a problem, then. And with the tasks in mind I mentioned above, 4:3 is definately superior to 16:10 which is what the Tab Pro has IIRC.
Battery runtime: I think they are pretty similar. The Tab Pro is a long runner and the Tab A uses 3% battery in one hour browsing (loading a new web page every 20 seconds which is my typical 'what are the news?' mode after waking up in the morning).
Now, the price difference is small (about 30 EUR on Amazon in Germany), but since I had to replace my old Tab Pro and was aware of its glitches I was ready to try something new - and haven't regretted it yet.