Depends on if you're racing competitively or just test and tune. The launch control isn't perfectly precise if you're trying to cut a good light (competition). Foot braking allows you to cut a light easier. If you're just trying to get a good time, then the reaction time doesn't matter at all, so you can make a sandwich at the light and launch 5s after it turns green if you want to
On a similar note, there's also some weird quirks with the launch control in that on some cars, it will randomly turn itself off. Mine did that to me a couple of times. If I were racing against a Hellcat, I'd bait him to stage first and set his LC and make him wait a bit to see if it screws up, then stage when his car gets out of LC just to throw him off his rhythm. Matter of fact, I try and do things like that anytime I'm up against a late model car with a similar LC feature.