The Atari 5200 SuperSystem
In the above Atari 5200 commercial you can see the original four port Atari 5200 as well as the trackball (advertised as coming soon). It gives you some idea of how big the trackball unit actually is as you can see someone using it.
Problems with getting affordable, reliable joysticks make the Atari 5200 undesirable to me despite my positive view of the system as a whole. It just seems like you are much better off getting an Atari 8-bit computer instead. Plentiful joysticks, pretty much all the same games, plus it’s a computer too.
Since the Atari 5200 is more or less an Atari 400 computer internally, you can get an 800, 800XL, 130XE or 65XE and be better off capability wise. Or you can even get an XEGS but that may be harder to find (i.e. more expensive). Though I’ll admit, the oversize Atari 5200 cartridges are much cooler.