Over the past few weeks, I have been replaying Supreme Commander, specifically the Forged Alliance expansion. There's just something about massive forces fighting over continents, making things explode like nukes, that never loses its charm.
I never played it's spiritual predecessor, Total Annihilation, but I like a few contemporary RTSes, like StarCraft, Rise of Nations, and Sins of a Solar Empire. Whether it's the fact that I use my left hand (therefore, hotkeys), or my programmer love for massive parallelism, I end up somewhat better at RTS than my friends.
The only problem is actual strategies. I tend to get stuck in a rut: I use what works, and not much else. I'm really good at the beginning, spreading out to claim resources and building an economy. I think I might keep building out too much before I start building up and getting better technology. But in the end, it works out in my favor. When the game ends, I look at the mass rate over time graph. I point out where my mass intake starts to take off compared to all the others, and say "That's where I started winning."
I guess I'm drawn to it now that I have a computer that can actually handle it without a sweat, cranked all the way up with about 8,000 things standing and moving around. It's also the only game that I know of that natively supports dual monitors without any kind of trickery. When you got a game going on dual 24" monitors, it looks like you're in your own private headquarters.
Supreme Commander 2 came out some time ago. Neither my friends nor I know exactly what it is, but it certainly is not Supreme Commander. Instead of fighting over continents, you're fighting in a backyard. Avoid it like the plague.