Agree with Dr. Sprocket about the ergos.
Another factor me me. Took a spin on a late model Harley. The low seat does keep the CG low and the considerable weight easy to manage, but I felt "low" in traffic and, compared to what I am used to, a bit dangerous. I am used to sitting up higher and being able to see. The low seat on the HD took that line of sight away. Just did not feel I could see as well, and the riding position was not one of control either. I don't want to lead with my head, sport bike style, but also don't want to lead so much with the feet either. Enjoyed the charismatic nature of the Harley engine though. Sure it is not fast, but it has solid torque and the exhaust note just speaks of adventures associated with drunk and disordely conduct
A BMW GS probably has the perfect riding position. It is tall, but who cares. It is a roomy and offers a commanding riding position. I ride dirt bikes too, so the big BMW I rode instantly felt familiar and good. Did not love the BMW engine though. It rolls out good power, but somehow manages to be boring to my taste. My FZ1 is pretty good, but a bit tight on leg room. My crash bars have forward "highway pegs" on them, which offers up a good approximation of an old Suzuki GS1000 riding position, with the feet just aft of directly below the grips. Works pretty good when my 49 year old knees start to complain, which generally occurs about 1.5 hours into the ride. Back to the future!
Thinking the functionally "perfect bike" for me would be the Duc Multistrada. They are just so darn ugly though.