Though there are many paths
At the foot of the mountain
All those who reach the top
See the same moon.”
This is an extremely controversial question and has generated much heated debate among many schools of martial arts.
The answer to this question is very subjective – students of any particular martial art tend to favor that one over any other (otherwise they would probably be studying the other martial art).
There are many different but equally valid reasons for studying any martial art, such as for self defence, for spiritual growth or enlightenment, for general physical health, for self-confidence and more. Different martial arts, and even different styles within a particular martial art, emphasise different aspects.
Hence ‘better’ really depends on what it is you want out of a martial art. Even given this distinction, it is still a very subjective question so perhaps a better one would be ‘Is Aikido better than any other martial art *for me*?’
This can only be answered by the individual asking the question.
An alternative way to answer this question is to simply say, ‘No, Aikido is not ‘better’ or ‘worse’ than any other martial art. It is simply different.’