I guess it's technically PTO powered.
On my relatively small (1.5-2 acre) lawn, three out of the four sides border unimproved woodland. Therefore, it's easy enough to simply drive back and forth mowing, using the mower to chop and blow the leaves to the edge of the lawn. Once there, they are in the woods, and rot away. They've been chopped enough that there's no real pile.
I only bring this up as it's free (assuming the mower already exists), which, compared to several thousand for a vacuum system, isn't that bad. Though I'm sure it's not for everybody.
It really doesn't take any longer than mowing the same lawn. And besides, seat time is good.