I think the raspberry pi 3a is the best raspberry Pi out of all of the models. They're thin, have a standard HDMI port, and a single USB port. Strong enough for what an Rpi should do, but won't break the bank You don't need much more.

They're REALLY good for running octoprint, and I had a couple laying around, so I designed this to replace the bottom layer of the c4labs Rpi 3a case https://www.c4labs.com/product/zebra-classic-case-raspberry-pi-3-a-black-ice/ It even has some air holes on the back just in case.

It's meant to screw into the frame along the Z axis, right above the control box. Works great for me. Hopefully it helps you.