I usually don’t care much about RDP version, as long as I can see the remote desktop clearly. I usually set the resolution to a small one with a lower color depth (15-bit). Recently, I realize RDP has been advanced quite a bit. I can get much better remote display quality. Below is a comparison of several protocols supported by Remmina.
I’m running Windows 10 VM in qemu. Video controller is set to virtio. On my Ubuntu desktop I use Remmina version 1.4.0 to connect to this VM. I noticed there are several options for color depth. Here are what they look like.
GFX RFX

RemoteFX

GFX AVC420

GFXAVC444

I’m looking for sharp text. For me, GFX RFX works best. AVC420 comes in second. I don’t notice any performance difference between these 4. That may be because the server and client both reside on the same machine and there is no network latency. I honestly do not know what the differences are between these 4 color depths.