The alerts kinda blow in my opinion. There just just about capturing territory which is what we do on a regular basis anyways.
How about....
1. Rings (lets say 30) are placed through out a map. The only way to score points is for a sunderer to drive through the ring. As soon as it does, the ring disappears for that faction. The first faction to drive through all rings, wins, or whoever gets the most by the end. So you can choose to just spam sunderers, or you can spawn just a few, but protect them with air and tanks. You can do the exact same with a galaxy version.
2. King of the hill. Each second the hill is in your possession, is another point for your faction. A new hill spawns every 15 minutes in a random location.
3. Capture the flags. 3 faction specific flags are spawned on the ground level, with each faction flag near their warpgate. These 3 flags can ONLY be captured by infantry units. You can jump in and out of a tank, flash, etc., but they MUST be taken by an infantry unit. You have to bring the flag back to your base, and the only way a faction can bring their own flag back to their base is if an infantry doesn't touch it for 5 minutes.
Now, there are 3 air flags as well, that can ONLY be captured by ESF, libs, and galaxies. Creates a nice alert for pilots and soldiers. These flags keep spawning until the alert is done.