Have you tried Supreme Commander? It's the spiritual successor to TA and is amazing. There's a community lobby, Forged Alliance Forever, that has a solid number of active players.
Gyle's channel on Youtube has some of the best replays around if you're like me and just like watching competitive RTS gaming.
The original Supreme Commander is not bad as well and interesting if you want to see the storyline that Forged Alliance sprang from.
SupCom 2 was hot trash. An attempt to make an RTS xbox friendly. Some of the worst voice acting in decades of gaming.