The 3B or 3B+ are the ones to go for if you want to use it for retropie. Loads of excellent pre-made images available and play around with to customise or you can download base images to set up yourself, but I would recommend downloading and playing about with existing images first to get a feel for the setup. Price wise this deserves heat, but pay a little more to get the 3B/+ if you want to use it for retropie.
3D Printing + Raspberry Pie?, lol, that sound's interesting ... Do you happen to have the schematics for that, by any chance?, or ... thanx. Also, out of interest, what version of Pi are you currently running your 3D Printer thing on?.
Not sure why this has "base plate" in the title?
Still has bluetooth, just half the ram and fewer ports.
They just say the 3 since it's the same SOC regardless, just half the RAM on this, still more than enough for emulating all those old games. Only need the 1 usb for controller, Micro SD still onboard for putting retropie and all the roms on. I should also say the B+ would be best, Just the B was the first RPi3 and has a slightly lower clockspeed on the cpu. 1.2 instead of 1.4GHz.