I bag mine with a mower and compost them with lawn clippings, food scraps and garden waste. I use the compost in our veggie garden. We have mostly clay dirt and it needs all the help it can get.
I have one of those big mulcher wagons. With 200 adult trees on the place we get lots of leaves. I pile them, add pure nitrogen and it a couple yrs have a yard of nice black dirt. Original pile bigger that a pickup and 10 ft high.
Down here in Missouri you have to add a lot of lime too as oak leaves are very acidic.