I don't like either. Standing starts are too difficult to manage in high-powered cars (especially with a DS2), and rolling starts were implemented very poorly in this game. Here's an idea: make on of the buttons a launch control button. Whenever you hold it down, TCS is turned on to whatever level you set it to. Once your off the line, let go, and TCS is off.
Rolling starts would be awesome if they just did it right. Everyone gets to go at the same time!!! Letting the lead car get a 5 second jump is rediculous.