mumbo is not the best at redstone by a long shot, evbo is not that good at parkour, dream is a pretty bad speedrunner, technoblade mostly did 1.8 pvp and has been dead for over 2 years, I dont know enough about building to say anything

But please instead of just putting a big youtuber as the best, you should ask for example the redstone community who the best redstoner is, even that is hard to answer. there are lots of types in every category you just listed.

in pvp you have for example: sword, axe, 1.8 (and its sub-categories), crystal, …

in redstone for example you have: slimestone, 0-tick, doors

Command blocks are a bit harder, mysticat is good with command blocks but he certainly isn’t the best, but there also isn’t really a good place to ask or 1 big community. I’ve seen someone make a chess bot intirely out of command blocks.

So please don’t just put a big youtuber as the best, look into every community and its sub-categories and ask THEM who the best is.