Re: Kokikai vs Aikikai
Aikikai is more of an organisation than a 'style' - not much technical uniformity within it.
And in any case the difference in quality of teaching between different dojos within any one organisation is so huge that it makes it almost meaningless, to me, to ask what style you should train in without knowing what teachers from those styles you're considering.
Visit the dojos and find out more about the individual dojos and teachers. Then you'll actually have something to base a decision on.