I’ve had similar thoughts about the iPad mini. I loved the iPad mini’s portability but I realized that I need the screen size of the full iPad to be able to use drag and drop. Getting one of the iPhone Plus models or the iPhone X pretty much negates the need for an iPad mini nowadays.
The 12.9" iPad Pro is beautiful but it’s roughly the same size as the 13" MacBook Pro. I think the 10.5" iPad Pro looks perfect. It is easier to take out the iPad Pro and doing some work on it while waiting in line when I’m running an errand. It’s a lot harder to take out my MacBook Pro 13" in the same scenario. I’ll need a desk or something to rest the MBP on.