I recently discovered Beyond All Reason, I'm having a blast.
It's a bit different from SupCom because it tries to be as faithful to the original TA gameplay as possible, with modern graphics / engine.
There's no campaign available yet but the game is pretty polished, nice AI to skirmish with and some epic online matches (few people online tho, but increasing as the game approaches a final Steam release).
Love BAR, it's my goto RTS at the moment. Excited about Sanctuary too... the vids and screenshoits look amazing