Engineer. Engineer has the most creative gameplay I find. There are lots of ways of using his kit to create chokepoints, save ammunition by electricuting enemies without shooting them directly or with turrets, bridges to nowhere to funnel enemies that you can jump off and make them walk all the way back, and more.
Scout is my go to when I want to rely on speed and skill over excessive/quick planning.
I remember eating an entire cheesacake by myself for lunch when I was in highschool. That was not my smartest decision.