My 2 cents:

Neither mascots suit Ruby. I'm not sure any mascot will. A ruby would work
as a recognizable symbol.
I am not an artist, but I admire people who are. The creators of the RTK
drawing and the anime character are obviously talented. Having said that,
here's my critique:

Bird: Would you trust your application to a frail little bird dumb enough to
sit in a human's hand? How do you know it won't take a dump when you need it
most? How about going South(North) all winter?

Anime: Would you trust your application to a silly girl? What about a silly
girl with large breasts holding a ruby and a stick? The first animated
version of Ruby Chan will be her wearing a school uniform and kicking an
alien in the teeth so you can see her panties. I certainly wouldn't wear a
t-shirt with her on it. You might as well wear the Power Puff Girls.

Pick-axe: Not too bad. Simple and handy. You can do a lot of work with it,
won't get in your way like an earth mover (read: commercial Smalltalk). Easy
to learn to use.

Just for the record, I don't care for Tux either. Duke (Java mascot) is
marginal, mostly because it is nondescript. The steaming cup of coffee
works, simple to draw, scales well, recognizable, etc. Just as a ruby would
be.

As father of the language, Matz should have the final word on any mascot.

Oh yeah    .   <-- there's a grain of salt to take with my opinion :-)

Regards,
  JJ