I have had the power flow on the 400 series and now the X series Deere, and manage to pick leaves and debris up quite well. Debris includes pine needles, pine cones, some acorns, wet and dry leaves, and some pretty good size sticks.
As to the question, how could anyone have such vast knowledge to be able to answer which has the most suction? How would one measure it? Too many variables to pin that down to a specific answer.
What I have works, and works good. But no way could I or would I say it is 'the most' even tho I might think that /forums/images/graemlins/wink.gif. I have no experience with any other.
I suspect (don't know) that the pick-up systems with the auxillary engine driving a separate 'blower' could have more suction as long as the mower deck and blades can deliver the grass and leaves over to the inlet of the 'system'. Mulching systems doubtfully can do that as they are designed to drop things down and chopped up.
You don't have an easy question to figure out. Good luck. /forums/images/graemlins/wink.gif