Quote from Magenera;192753:
I put it this way.
Goku new opponent = his limit, till he gets stronger by death/training/ new skill.
Superman new opponent= Superman adjust his strength to be a bit better with out killing.
Goku has limits. Superman limit has yet to be reach.
Goku's potential is limitless.
And his power grows quite exponentially.
Saiyan Saga to the Frieza Saga, for example. That boost to Super Saiyan just put him on a whole new other level. And his power kept growing while still just a Super Saiyan. In the Cell Saga, for example.
Every new SSJ transformation brings Goku to a whole new level and he still keeps on training and increasing his power.
I feel like Superman's growth in power is slower and more constant.
Also, try not to double post, haha.