What would you guys pick between these two? I might build a .300 Blackout SBR but this Sig is badass in both forms. I have been wanting to get a PDW in 9mm as well but the .300 was going to come first.
MPX 9MM SBR
https://www.rainierarms.com/sig-sauer-mpx-9mm-30rd-sbr/
MCX .300 Blackout SBR
https://www.rainierarms.com/sig-sauer-mcx-rattler-300blk-sbr-5-5/
Check out the CZ Scorpion EVO. I have one and love it. It also has the H&k style "bolt slap".