I second the Nvidia Shield but have never used one! Seems to have more grunt by all accounts, as well as HDMI out.
I have a Samsung Tab S which is a nice tablet, but unless you use a messy workaround you'll probably get FPV lag until DJI sort out their firmware/app issues.
Samsung do seem to install a lot of crap on their devices too, and are kinda slow with Android updates.
The problem has been narrowed down to Google Play Services causing the lag. The known fix is to "Roll-Back" any updates and turn off auto-updates so it stays on old version. This removes the lag experienced.