I've been on a RTS binge lately. Been playing Warcraft III and Soulstorm mostly, which are probably the two best games of the genre in my opinion. It's also a little disappointing that these two games will never see proper sequels, Blizzard pretty much ruining any chances of Warcraft 4 with WoW and Dawn of War 2 focusing more on squad based gameplay rather than larger battles.
There's a couple decent games that are similar to WC3 like Dragonshard, but it focuses more on the RPG aspect and lacks in the strategy department. I can't think of any game that's like dawn of war (large scale battles with a heavy focus on squad development) but I do enjoy the sequel and I'm looking forward to Retribution.
But I think Warcraft III will probably always be my favorite, the perfect blend of strategy and rpg elements. I really wish they would update the game to support widescreen and maybe even move it over to bnet 2.0 because I doubt they will ever make a sequel for it, which is ridiculous but hey MMOs make more money!