I have a gigabit connection between my PC and my server (iperf3 tests show ~930Mbps) and I want to be able to transfer large files as fast as possible. The hard drive on the server is connected via USB3 and it is a Rock64. With ssh (I am using btrbk with ssh) I think the bottleneck is probably ssh because of high CPU usage and hot temps (~60C). I did disable compression although I think it's disabled by default (put it in ~/.ssh/config). I only got speeds of up to 350Mbps maximum but it fluctuated a lot, I don't think the Rock64 can handle the ciphers with that much data. And after a while it slowed to a crawl (less than 1Mbps) for some reason that I'm not sure of. Restarting the transfer worked. (May not be relevant to the question).
I need a cipher that can do about 480Mbps at the least. You can probably lower that number by a bit due to realistic USB3 speeds though. Not too worried about security because it is just Ethernet connections from PC > router > server but no/weak encryption would be overkill anyway. So preferably the most secure cipher that can do above speeds.