IMHO there will only be one RPi killer, and that's another RPi ![]()
RPi4 is not the best spec thing in the market, but only comparing hardware specs misses the point about RPi boards. They have massively better long-term software support, so they are reliable and continue to improve with age.
Although bitrate is probably involved somewhere in the overall scheme of things, I'd guess internal bandwidth between IP blocks is where things are on/approaching the limit, so (repeating myself) some overclock might be helpful.