Well, for my sins, I'm joining the GoPro cult Our company had a one-time 25% off GoPro so there's a Hero7 Black coming next week.
It seems that the GoPro SuperSuit is the most common housing at least for starters? Are there any others I should look at? Like the OP, I'm planning on very casual usage, mostly to show friends and family what I see diving, not anything remotely serious.
A cheap knockoff housing is actualy better
With the supersuit you have to remove the lens cover that normaly makes the camera waterproof.
With a knockoff you can keep the cover on so even if the housing leaks your gopro still has a chance.