Depends on what type of RTT you use. I have a hard shell and it takes about a minute to deploy it. You also don't have to hassle with a dirty cover and/or a dirty zipper that doesn't play ball when storing away the tent.
But on the other side, most hard shells are more expensive than soft shells.
For both types of tents I assume that annex rooms are the same and therefore a PITA to set up compared with the actual tent. That was the one thing I didn't like on our recent Colorado trip, but we needed a place for the dog to sleep.
From a general perspective I like being away from the ground, not having to crawl into a ground tent (I still have my tunnel tent, though), the ease of deployment, and the fact that it is always with me.