There are 4 RTSs that I have ever played in my entire life. In chronological order : Total Annihilation, Starcraft, Warcraft III and Dawn of War. I’ve made an analysis to compare the main part in RTS which is the units. Frankly, Total Annihilation, which is the oldest, has the most type of unit available.
Below is the table showing the unit type versus RTS games.
The winner : Total Annihilation. The oldest of them all, 13 years of playing. Plus, players can download 3rd party units. I don’t see how other RTSs can add unit in their games. Looks like an analogy for the PC vs Mac. Starcraft is well-known to gamers as well as a Windows PC. Total Annihilation is better than any other RTS which is quite similar to Macs, but people didn’t know about them.