I wish to disagree with Bobert re. a bagger.

With 1.5 acres to mow a bagger would be a royal pain in the ass - you'd be stopping every few minutes to empty it.

A mulching blade is the way to go IMO. I've been using one all along and granted it creates a few clumps here and there but overall it saves a lot of time and labor.Unless your goal is a super manicured lawn on which you can play croquet mulching is the way to go.