Top of the line means exactly that... the model at the top that is currently available..
Now are you ready for this... the Roland arranger keyboard at the top .. still available is the E-A7
The prior TOTL before being discontinued was the BK9 ..
Nothing to do with the price point..
Now the best of brand can be another story... Personally I would say the G70 (E80), followed by the BK9 and then the E-A7.. All are great keyboards..