Hold the line for the mainstream stuff.
The Z2 Extreme is essentially the HX 370 with better power management between the GPU and CPU since it has 8 cores instead of 16. In all the benchmarks I have seen the 890m gets power starved under load on CPU intensive games which drops frame times significantly as it struggles for power even with the awesome efficiency improvements the HX 370 is a monster of a chip for a handheld that needs lots of cooling.
The A1X makes for an amazing device though. If you can justify the price to own the most powerful handheld on the market right now it also ticks a lot of boxes off on the "must have" check list.