As far as RTS's go, I dont like them. Too many of them do their systems too incorrectly, or just dont plain make any logical sense, or reason. Dawn of War (all the expansion packs, consider this a recommendation for Dawn of War + all of the expansions), does some critical things right, which makes it stand out from the crowd.
First, it actually focuses on strategy for the most part. Instead of spamming 1000 tanks at your enemy (im looking at you Ruse), you actually have chose a limited number of units to bring into battle. Meaning, every man, tank, and resourse is valuble, and losing any of the above can cost you the battle. This tension, and balencing on the brink of death keeps tension high, as players must constantly have to outdo their opponent on a mental capacity, not necessarily on a quanitative capacity. This conbined with some rather unique in game mechanics, such as morale, means interesting strategies can arise, when those similar would fall flat in other RTS's.
And secondly, the game is able to keep a consistent feeling, tone, and atmosphere. Even for a strategy game, this is important, nothing takes you out of a game more than an interface, so even immersing the mission select screen in 40k does its job. Everything is plastered with 40k jargon and logic, a dark universe of war, death, and betrayal. As well, the game itself feels fitting, with you not taking resources, just getting requisition points to send in more troops, as you are successful in conquest, just as an example of many different things the game does right.
The game is fitting, and is able to keep a consistent feel to gameplay and atmosphere. For this, I must heartily recommend Dawn of War to RTS fans, you will not be let down.