For reaction time, I think a few of the most targeted nootropics I'd consider are Pyritinol, one of the "-afinil" drugs (Armodafinil, Modafinil. Adrafinil), and Caffeine. As a secondary consideration, possibly Sulbutiamine, DMAA, ALCAR, and Ginseng.
Pyritinol is one of the few nootropics that reportedly improves reaction time.
http://www.ncbi.nlm..../pubmed/2135070 All the others I mentioned are often purported to have notable stimulation of the CNS and areas of the brain involved in cognitive arousal and alertness. Some type of anxiolytic like Picamilon may be helpful to suppress anxiety that might be caused by the stimulants.
Although they have no direct benefit on reaction time that I'm aware of, I still think some type of racetam could be helpful. I'm a strong proponent of racetams, it seems like general cognitive improvement would be helpful in any situation.
Some of it may be genetic, but I think good conditioning is a far more significant factor than genetics. Some methods I think may effectively improve reaction times include juggling, wind sprints, using a speed bag, jumping rope, and dancing. A video
Beyond Speed by Health For Life featured many techniques for training reaction time, but the only one I readily recall involved watching a 30 minute TV show and punching every time the camera angle changes. I think strength training would help too, anything which improves explosive strength of muscles may help as much as mental training.
I'm not suggesting you should take all of those supplements at once (or any of them). That's just an overview of a few things that seem to offer the most promise. You'd probably have to do your own testing to find out which ones affect you in the most favorable ways.