For me, it was the game Rocket Jockey released by Sega Soft in '96. It was perfect. The game featured a surf rock soundtrack by Dick Dale. The entire premise of the game was to ride around on rockets and using long cables to yank your opponents off theirs. Referees were also fair play. I don’t think I’ve met anyone else who has played the game, so if you have, let me know!
I’ve tried both Supreme Commander and Planetary Annihilation.
I think what mostly bothers me about updated versions of the concept is that there are too many “this type of unit counters that type of unit” pairs. You’ll start a campaign level, build yourself a nice mixed bag of versatile units, and then an enemy will show up with a horde of some specific unit X that completely overwhelms you, because you didn’t have enough Z artillery which is like the only effective thing against X.
I rarely had that problem in the original TA. Generally, all units are vulnerable to all other units, so you have to use geography and consistent resource-denial strategy to your advantage.
I recall getting stomped online by guys that would amass 3-400 little flyers and just rain hell on you before air defense could knock them out in TA.