1. Front Kick (I think this is the best)
2. Roundhouse (Extremely effective if it lands correctly on the
attacker's temple, but poses a great threat if
missed/mistrike.)
3.SideKick (Saves you time from turning your body to hit
attacker(s) from the side)
This is pretty much what i think is useful in a self-defense
situation, other kicks like 360 degree roundhouse, rear horse kick
etc are useless.
Share yours here.
In a "real" situation, unless you are hella sure of your own
speed, power, and stability, kicks above the waist are very
dangerous to do. If you get parried, blocked, or even shoved while
you are attempting a high kick, you could end up on the ground,
which is not where you want to be. Also, too many martial artists
are trained to step into a high kick and whack you in the family
jewels.
Actually, I wouldn't recommend kicking at all unless you are
confident of flooring your opponent with one kick. TKD fighters in
the 70s were feared throughout SE Asia for their frighteningly fast
knock-out kicks. TKD fighters today, however, generally cannot
generate enough power to be effective because the emphasis has
shifted from KO fighting to point fighting.
On the other hand, "dark" kicks (a.k.a. hidden kicks) are
actually very useful. These are kicks which have zero or
almost-zero telegraphing. Even experienced fighters are usually
unable to defend well against such kicks; they have a very high
chance of connecting cleanly. I have never seen a hidden kick in
TKD, though the horse kick in Taekkyun is sort of a hidden
kick.
Most hidden kicks are shin or knee level kicks, such as this one.
(Actually, this is not really a hidden kick; a hidden kick involves
even less body movment than this.) There are some martial artists
who can kick at waist or chest level without moving any part of
their bodies besides the kicking leg, however.
In the final equation, like Pallova has said, there is no such
thing as a useless technique. It's really whether or not you've
honed it into a deadly weapon. That said, some moves (e.g. TKD
reverse kick to the head) are more difficult to pull off than
others (e.g. boxing jab) and require a lot more dedication to make
useful.