I'm not aware of any other space systems outside of Star Trek with the same scope. Feel free to recommend some, though.
I love Battletech. I spent many of my formative years playing Battletech. But it doesn't, let's be honest, have much tactical depth. It's more of a beer-and-pretzels+ game. There's nothing wrong with that, but if it's scope and depth your group is looking for, I'd go with with FC. I don't think you can go wrong there.