I guess it's your own preference.
ATX's AI is far superior to RB4 in my personal opinion. I never have to tweek a thing in the script. You set it on full A.I. and it babysits itself.
If you're used to RB4, switching over to ATX won't be too much of a problem since the interface is slightly similar.
img hotlinked from the ATX support forum for one of the sites we worked on
