My oldest and smallest friend has long been into 40K and got me playing some 9th on Tabletop Simulator (and once in person with his other army (go nids!)), and I've been much happier with the rules of 10th ─ that I don't need to memorise a huge list of options for every command phase makes things much smoother for me.

I'm used to complex games ─ I play MtG, I run complicated trpgs ─ but I'm very happy at the lower cruft here to get my head around a new dangerous money hole