Mainstream Superman
KC Superman
Superboy Prime
Superman Prime (with guardian amp)
Golden Superman Prime
Amped Superman that fought Anti Monitor
Superboy
Bizzaro
01. Golden Superman Prime
02. Amped Superman that fought Anti-Monitor
03. Superman-Prime (with Guardian amp)
04. Superboy-Prime
05. Mainstream Superman (Pre Darkest Knight I would have put him above 06. Superboy-Prime)
07. KC Superman
08. Bizarro
09. Superboy
Probably all over the place and wrong, but at least it hopefully kicks off the discussion.
It's hard to rank them, because with some of the versions you have to go with theory / potential / implied power. Like with Golden Superman Prime, who has spent the longest time in the Sun. If you view all Supermen equally, then all Supermen would be what he is, if they went through what he went through.
KC Superman is an old, elseworld story at this point. At this point I wouldn't put him above modern day Superman, who has gathered many great new feats.
Amped Superman, who fought the Anti-Monitor is tough to rate. I guess we're talking about the Infinite Crisis arc, right? He did fight the Anti-Monitor, who absorbed power from his own universe to attack Superman and Superboy. But how much power from that universe did he absorb? Anti-Monitor killed Supergirl, but started to weaken and wasn't able to kill Superboy. Still, Silver Age Kryptonians were a whole another animal.
Superboy-Prime also faced the Anti-Monitor, but I liked to think that Anti-Monitor was already ****ed up from all the prior fights he had.