Tuff call. I've owned a Mustang Premium, & a Avatar LE in the past, both were very fun games. If the Mustang was a premium I would have voted for it hands down. But, since it wasn't, I voted for Avatar. Avatar is all about stacking multi-balls, it's a fun pin for sure! It is very similar to IM in a lot of ways. Plus it has great call outs from S. Lang that might help draw some attention to the pin. CSI I've only played once, so I really can't comment on it, other than I remember it had a lot of different shots, & I thought the centrifuge was pretty cool.
Also, are Chevy, Dodge, Toyota, etc., etc., guys/gals going to play a Ford Mustang pin? I know pinheads will, but the casual non Ford guy might just keep walking.

Avatar for the Win!