A few guys at work interested in trying 40k, best armies to print for learning the game?

I played a handful of games a couple of years ago, but never had an army of my own. I’m personally leaning towards either Necron or Tau, but my friend has a 3D printer and a lot of experience with both resin and filament, so I figured it might be worth printing off like two small armies to just leave at work, so that anyone can try the game out, and we all start learning the rules together.

For learning the game, would it be best to just have like two Space Marine armies? And any suggestion for pre-made army builds, just to get us playing sooner than later?

Oh, and also I’d heard there was a discord here? I searched older links but they were all expired