The type of bike you get determines the type of ride. Seat and suspension along with body position determine comfort. Engine size, type and gearing determine the acceleration and top speed based on power to weight ratio. You can have a 1200 sportster that is only slightly more comfortable than a vtwin sport bike but much slower. 1. Decide what type of riding you want to do. 2. Decide how much you want to pay for bike + insurance. 3. Pick an engine performance you are comfortable with within the type of bike and budget you decided on.