Don't just consider Total Annihilation, grab it with both hands!
If anyone is still on the fence about TA, maybe this is the push you need. You will NOT be disappointed.
I thought I read somewhere but maybe I am wrong, that TA is kind of overwhelming for an RTS newbie. On that basis I've thought about picking it up for "someday" a number of times but I keep thinking with so many other games to play that maybe someday would never really come to pass anyway. The fact that it is regarded so highly as a classic does nag at me though.
It was my first RTS, so I don't find it that bad. There are only two resource units, so that is simplified a lot, but you need to manage that economy. Play a few skirmishes on easy and get the feel of it.
The one thing that you have to get used to that is different from other RTSes (and what some people may find overwhelming) is that you have to keep building, a lot more than before. In other games, you make say, one barracks, one land unit building (etc) or maybe two of each, in TA it's not unheard of to build six of each. You can easily have 10 construction units assisting each construction building, to increase the production rate.
Keep your economy balanced and keep cranking out the units.