One word - mulcher.
If I had to bag, I wouldn't mow... the tradeoff of once a year having to dethatch is a very, very good compromise for me.
I've got a Craftsman 21" with a Briggs 6.5 - push, not self-propelled - tried the old neighbour's self-propelled once... it'd probably help if you had a big rural lot, but the ins and outs of an urban lot with trees and other features just meant I ended up trying to hold it back a lot to make turns and doing burnouts on his grass instead. And all the gearing and drivetrain almost doubles the weight.
My .02 - YMMV.
Bren R.
