I personally think she might enjoy Kung-fu,
it's stylings are much like dancing and tend to be defensive.
It's a more symbolic & flowing Martial Art, one that a little girl might take to,
and still be practical over the long term.
Aikido takes lots of disipline, Thai Boxing is too hardcore
Tae-Kwon-Do might be too agressive, as with pure Karate. (these are considered "hard" styles)
Kenpo might be nice as it mixes in Kung-fu (BTW, I used to teach this & I'm about to start it again)
And Judo is very practical but might not be for a 5 yr old.
I would suggest Jiu-jitsu, Kung-fu, or Kenpo. (these incorporate more "soft" styles)
Those styles are not too agressive and are easily learned.
And the movements within would be interesting to a little girl.
And god-knows keeping the interest of them is difficult.
