Lenght of rod, is like ... what you like after the lights go out ... 'It's in the eye of the beholder?'
I've had rods 18 foot long, and cast a 20. Both beat the heck out of me. For very special situations my 15-16 footers never see water. Longer is not better save for the situation 'demands' same.
Just my .02 cents.
Guys who love the longer rods? Bless 'Um. Not my cup of tea.