You will not like green tree pythons. They are not as energetic as ball pythons and them being aggressive snakes as a whole is a myth. Maybe biaks are an exception but its more to do with the individual snake and wild caught vs Cbb.
A good alternative to green tree pythons are carpet pythons. Active, more energy and can be quite nippy as babies(or so I've heard, I've never come across a nippy baby). And because they are both Morelia they look very similar except for color/patterning.
Just a comparison to show the similarity