The fact that we're on this forum indicates at least a bit of preference, of course. But Dust Warfare is increasingly becoming preferable to Warhammer 40K. The short list includes:
Rules that at least have some guidance, rather than the product of a soviet of duelling company fiefdoms each putting in an equal amount of new rules for the sake of appearances.
Errata on said rules, instead of stoney and truculant silence.
Reasonable prices on minis, and particularly on models!
And now, the latest reason: Anyone besides me seen the price of the new 7th edition codecies? $50 USD! For nothing more than the previous codex template, with a hard cover. Personally, I find this intolerable; since I own 11 40K armies, that would be $550 USD to codex myself up over the next 4 years. That's almost as much money as I've spent on all of my Dust material, including the 1st edition Tactics and every supplement for it.