For the micro, I'm going to go with the STM32F769.  This is the device mounted on a few different graphics dev boards made by ST.  It comes in a couple of packages that fit my goals.  The STM32F769NIHx comes in a TFBGA216 package that has a 0.8mm ball pitch.  The device can be completely fanned out on a 4 layer board with 4mil trace/space.  There is also the STM32F769BITx that comes in a LQFP208 package with 0.5mm pin pitch.   This part is actually part the JLCPCB SMT process and at the time of this writing actually has stock.  

The STM32F769 has 2 lanes of DSI and LTDC-RGB888 (although both cannot be used at the same time) and can support SDRAM as well as QUADSPI.  Enabling all of these does not step on any of the other hardware peripherals meaning if you want ethernet or audio you can have it.  The display interface (LTDC or DSI), RAM (SDRAM - FMC) and flash (QUADSPI) make up the hardware requirements to run TouchGFX.

Finally using the F769 means I would have access to all the code and examples created for all the demo boards that use this device.

I think it would be cool to use the STM32H745 which is the M7/M4 combo core.  It can support graphics, but does not have DSI hardware capabilities.  The dual core would allow you to have the M7 running the graphics side of the application, giving you an entire free M4 core for any real time stuff.  It would be awesome if ST had a dual core part that has the advanced graphics stuff on it.

I'll post up next an example of fanning out the F769 TFBGA package.

Until next time...