I would prefer automatic transmission when driving with games, but in real racing, most nascar and drag strip cars use manual when racing -but they say formula 1 uses a automatic or semi automatic to be precise.
I overall prefer the manual transmission if it is an option and I already know that Nascars and Drag racing cars use manual transmission. Formula one cars are semi-automatic because they have paddle shifters but they don't have a clutch.
I still prefer to go automatic transmission when playing racing games. On some games, the manual transmission shift is not that perfect. Also, you have to mind a few other controls instead of having none.
I think automatic transmission can be good in many ways. You can see that some of the time it's good to have it in the game.
I find the manual transmission in games a little complex. It isn't exactly as we do it in the real world. I prefer automatic for racing games.