they are all basically trans levelers but i do find kal kent and guardian amped prime to be higher on the scale.
the way i see it prime is physically too much for darkseid to handle, he will pumle him worse than HP Doomsday did.
kal kent vs thanos is also in favor of kal kent, he has feats such as slowing down a charging galaxy and stop it with help, containing solaris itself inside his force field, breaking time while greatly depowered, and there was a statement he cleared his world from all the forces superman could not which include darkseid doomsday and brainiac.
Guardian amped prime vs thanos? again i dont see thanos whitstanding such a brutal force as guardian amped prime, his force fields will be shattered and i just cant see him being able to whitstand such physical assault.
kal kent vs darkseid, again kal kent has too many powers like his force field and telekinesis and energy manipulation , all of them at star - galaxy levels.
also i remember while being depowered he swap firestorm away with just his breath, and stated he can destroy a giant red star at that point with only his breath.
i just find his feats to put him above both darkseid and thanos.
Prime is just a physical beast which probably can give skyfather a headache
You do know that either Darkseid or Thanos could bfr Superman Prime into a red son right? Both of them also have stansmutation powers and could potentially create Krytonite to Weaken the Supermen.
what? you do realise that the bfr part can work vice versa dont you? and you realise guardian amped prime will be right in their face within the next second? and you do realise if anything kal kent can bfr them the easiest? you dont wana go into the bfr department because both of them will be traped in another dimension by kal kent.
do you even aware of the fact they are both imune to kryptonite?