I think both have their merits, their advantages.
Shrinking is more personal, obviously. It creates a new playing field for the tiny, a new world to have fun with. You can hide behind almost every mundane object, but a lot of those can become dangerous too. Also shrinking is best for unaware scenarios, and the 1 on 1 situations.
Giants is different cup of tea. The reality changes for the big one and now city becomes his playground. It’s less intimate, but it has potential to be very personal with some inventive thinking. I can imagine a partially destroyed, evacuated city in which I’m hiding in one of the abandoned houses as the giant sweeps them one by one to get me.
Currently I have a slight preference towards the giant scenarios. But obviously, I like both.