For any Warhammer 40K fans here, what is the best 40K game you've played and why?

DOW1: Dark Crusade. Because open campaign map and because Necrons.

Chaos Gate because of music and cpt. Kruger's voice

I would hesitate between three titles - Rites of War (my favourite title amongst WH40k titles from 90'), Dow 1: Winter Assault (my favourite amongst DoW 1 for outstanding campaign with my favourite Imperial Guard) and Dow II: Retribution (I LOVE dialogues from Ork's campaign, and finally there is Imperial Guard - yes, I know that campaign is the same for all sides, but I still like this game).

Ah, I really can't decide for only one :P

This is exactly right.

DoW1 Dark Crusade, probably.

DoW1 vanilla was ok, but you can only play space marines in the campaign.
DoW1 Winter Assault had this weird system where you can switch between factions in one of the later campaign levels, which was pretty janky
Soulstorm just felt wrong to me. Idk why, but it felt like an inferior Dark Crusade

Space Marine was a nice brawler, but it was too short and the last boss fight was a QTE, which was lame.

Final Liberation was ok for its time. Its a bit dated now, and they never got around to adding the other factions, but it did have some nice FMVs and its not often you get to see titans in action.

I could never get into Chaos Gate. Didn't feel right to me. Ufo Defense had better gameplay, and the fact that you had extremely limited forces made it pretty tedious.

I didn't like the game play of DoW2; there was hardly any building, and the retreat option feels way too powerful.
Most fights go like - mass troops around objective, press x to retreat with hardly any losses. It felt like a slog
Not to mention that the Campaign for Retribution was just all of the factions copy and pasted. Play one campaign and you played them all.

Warhammer 40K Space Marine for me :)

I'm more of a Black Templar fan but the Ultramarines are stil pretty sweet :P

The combat in Space Marine is some of the most brutal, loud and chaotic stuff I've seen out of all Warhammer 40K games. Story is pretty interesting too :3

Also...that soundtrack is amazing.

Final Liberation because: both strategy and tactics, many units, large scale battles, titans and aircraft, artillery and COMMISSAR HOLT!!! :)

DOW 1 Collection, with a special mention to Soulstorm, because it adds the Battle Sisters !

Dawn of War: The Dark Crusade. Period.

Edit: Oh, okay, we're supposed to add a reason... because it's a fast yet deep RTS with hugely diverse but well-balanced factions, massive battles and a great, albeit rather light, take on the universe.

And ah crap, missed my chance to make a Fire Warrior joke. Which I actually played just last year or so again and which is even worse than I remember. Don't know what jackass decided not to include any music during gameplay. It becomes a lot more bearable with the Dawn of War soundtrack playing in the background. By the way, I always wondered how the reception of the PS2 version could possibly be so (by comparison) good but having played Killzone HD by now, which was the PS2's flagship shooter, I get it now. Fire Warrior might actually be the better of the two.

I've had my eyes on Battlefleet Gothic Armada for some time now. Looks like it does a good job at capturing 40K...If only It was on GOG :o

Not to mention the extremely fitting soundtrack that makes you believe you've been transported almost 40000 years ahead into a dystopian universe:
https://www.youtube.com/watch?v=ohw704HkIKU
Though the great music is present in all die Dawn of War 1 titles as far as I can remember.

If only the series ended with DC. I didn't like Soulstorm at all. The campaign was similar to DC's only less fun somehow. And the 2 new factions along with flying units for each faction fit poorly into the series imo. It wouldn't have been so bad had I not been playing a lot of multiplayer at the time, because when Soulstorm released DC's multiplayer lobby started to dry up :P

Dark Heresy
Set in stone games have nothing on the awesomeness of the creative imagination of rules lawyers and egocentrists.

Oh I forgot about Firewarrior.
And for good reason, that game was mediocre.

Dawn of War: Soulstorm with Tyranid and Daemons Mod is the pinnicle when it comes to Skirmish and Mulitplayer.