In looking at martial arts styles that develop kicking ability, I will say that Taekwondo is the best style for developing kicking skill. Now, there are many styles of martial arts that practice kicks, but Taekwondo specializes in kickboxing like boxing does in punching. Kicking skill is harder to develop other skills. The flexibility, dexterity, timing, accuracy, and distancing, needed for kicking an opponent harder to develop than many other aspects. When people looking at the sport of Taekwondo, they will criticize and say that the sport is impractical forgetting to look that the unique aspects that one can derive from that sport (as in all combat sports). Having been a Taekwondo player myself, I can say that the kicking skills of high level Taekwondo is way up there. Because the emphasis is on kicking you have better cardio (an olympic style match is 3 rounds). You can punch to the body, but the opponent wears a chest protector. This makes it difficult because you have to be able to punch really hard to get through it. To illustrate, check out this video to see I use my kicks.
Shidokan Technician Video