I have both. I initially bought a Nomad 883 Pro, and although it was great, I found myself needing to do parts that wouldn’t fit on the bed. If it was just a few here and there, I could have made it work (and did for a few).
Advantages of the Nomad: Super easy to get started with machining, more precise, quieter.
Advantages of the SO3: Much larger, can cut just about anything, much more power than the nomad.
So as will says, if you’ve got a variety of projects they can be quite complementary. Because of my particular project mix, and my inability to stop myself from tinkering, I find myself using the SO3 almost exclusively these days - not because the nomad isn’t great, it just isn’t big enough for my projects.