Really? Wow, you'd better not tell all the dojos affiliated with Shioda or Tomiki that.
The two biggest schools to come from pre-war students of Ueshiba. That's not to mention Mochizuki, either. I'm not sure how large Yoseikan is -- maybe they have more members in Europe, but I don't know.
Unfortunately, you're wrong again. It is well documented (thanks to Stan Pranin) that Ueshiba Morihei's main and central martial art was Daito ryu. Period. What made Ueshiba great? Daito ryu. What made Ueshiba powerful? Daito ryu. What did Ueshiba teach pre-war? Daito ryu. What kind of rank did Ueshiba award to pre-war students? Daito ryu. Thank you Stan for your laborious research.
It's like saying that it is well documented that Chuck Norris studied Brazilian Jiu Jitsu. Well, sure, he worked out with BJJ some. Wasn't what made him great or famous, though.
If you're really interested in this stuff, study Daito ryu.
And if you want someone capable, great teacher, fun, and worthwhile, look up Howard Popkin.
As someone else noted, Hiroshi Isoyama came from post war and started studying Aikido in 1949.