My suggestion would be to pick whoever you think teaches better, aside from thinking about styles name, mainly because if your chosen teacher is any good he will have broad horizons, having studied under different Masters, from different styles.
Here in Italy Aikikai is, like someone said earlier, going in a worrisome direction, taking several important things out of the curriculum (kicks, kick defence and koshinage/hip throws, other than de-emphasizing Aikiken and Aikijo) which is further maiming our Art...
From a self defence point of view, everything has taken a full step across from a few years ago.
I generalise here, but IMO...
Ki aikido now often barely resembles a martial art at all. It's like some kind of paired kinetic yoga.
Aikikai now often occupied the ground that Ki aikido used to. It still has attacks and defences - often heartily applied, but it is more concerned with teaching philosophical principles than combat.
Many of the harder aikido schools seem to be starting to call themselves aikijutsu just to differentiate themselves from the softer styles.
There are two frightening thing about me feeling sad that aikido "isn't what it used to be".
The first is that in in terms of its life, I haven't been in it particularly long.
The second is that I am a massive wuss, and yet I'm considered more fight-oriented than most aikidoka.
I believe the best suggestion is to go to a dojang and look for yourself! ;-)