I'm not going to mention a particular model but rather specs to look for.
Bigger screen is better, as is Golden Ratio aspect ratio. I have a 9 inch 3:2 tablet and I think it's the best for iFly presentation. Lots of room to display stuff in Landscape. And, when in Portrait for Plates, its display is 1 for 1. No scrolling Plates up and down.
I have an 8 inch, 4:3 that I also use in Portrait. It's fine, but I wish it were 9 inches for Plates. (A 10 inch would be nicer, but too big for our cockpit.)
Brightness. You need a tablet that you can see in your plane with all the reflections/sunlight/etc. My 9 incher is 525 nits with a polarized screen. I would like it if it were a little brighter, but it's always been readable in the cockpit. My 8 incher is down at 380, non-polarized. It's good most of the time, but I think the old Nexus' are brighter. I read that the new Samsung Tab S2 with its AMOLED is good in sunlight. (But expensive.)
You want to check if your screen is polarized, because if you wear polarized sunglasses, that will limit which way you can use your tablet. (Portrait or Landscape. We can only use my 9 inch in landscape when wearing sun glasses.)
I don't think RAM matters much anymore with most up to 16GB or more. But an external SD slot is nice and there's a free Android app that can put iFly on the ext card if necessary.
Update: Look for a tablet that the xda-developers have already rooted. You might not want to root right away. But even if you don't install a custom ROM, there are a lot of things that you can do rooted that really improve tablet performance. (E.g., on my 8 incher, I'm running OEM ROM but rooted. Root has allowed me to debloat the OS to the point that I can go for days without battery drain in standby. Debloating makes things go faster too.)
Update 2: Price equal or less than $200? That way you can buy two of them for IFR. (Backup and one for Plates and one for Nav.)