Aikido derives, in a nutshell, from defense barehanded samurai. Let me explain, the techniques of aikido do this: one shakes your hand on the pulse and defense with the technique makes you fall to the ground. Try to do it in reality, one lets go of his hand instinctively and the technique is not applicable.
But in ancient times had a sense, the samurai had the sword on the side, sighted an enemy and tried to pull out the katana, the enemy seized the wrist to stop him and any movement did not let go because he knew that if he was let go skewered, from that moment born aikido techniques and become applicable. So aikido makes sense, it is a fight applicable in certain circumstances, the problem arises when those circumstances change, saying that it can be a unarmed combat system that is not.
Watch a Steven seagal demonstration and watch a Gracie fighting in Pride. Then decide which looks more legit.
aikido doesnt work so your better off doing jiu jitsu.
depends what you are looking for and why. Look into both check out a few classes. Talk to the instructors. Find which is best that suits you. Only you can decide such.