What is your application, view still images (photographs), play videos, show a panel with data?
I have in development a project to play videos using STM32H747 with MIPI screens, and also another one using an RT1064 with RGB screens. With the H7, hardware JPEG decoding can be used to make an MJPEG video player. With the RT1064 you could decode by software or work with uncompressed videos.
I understand that all these microcontrollers with output to handle RGB or MIPI screens, do all the control of the screen by hardware, so the performance must be high. Another more powerful alternative is to use the RT1176 (when available), this is a Cortex M7 at 1Ghz, with RGB output.
I think that with all these powerful microcontrollers, and using an external SDRAM memory, you have a high enough performance for any application displaying images, data or video on small screens with resolutions that do not exceed HD (1280 * 720).
The only problem is that right now, due to the global semiconductor crisis, I highly doubt that you will find any of these microcontrollers in stock. I was lucky and before they completely disappeared from the distributors, I was able to get a lot of RT1064 and STM32H747. I had to invest a lot of money, but I do not regret it, now I have stock to work during 2021 and part of 2022. It is assumed that by mid-2022 there will be again stock of 32bit microcontrollers, but there is nothing certain.
Those of us who were far-sighted, spent money (much more than usual) and bought, now we can work.