Most of my ball pythons act like...ball pythons. I do have a few outliers on both behavioral sides:

I have a few that adore being held and will quickly slide up to my shoulders and perch there in a stationary position as I go about my daily chores; Once they get comfortable I have a devil of a time prying them off...

Then I have a few that think they are world serpents and I'm just a lowly cage cleaning monkey who deserves to be bitten for disturbing their slumber...

I have noticed a heritable polygenic component to behavior among my different lines, but, I don't see anyone advertising their $5K normal ball pythons with an 'extra nice temperament'--so personality is not as highly valued as looks to your average owner.