Funny, I thought for sure my son (12) would want to see LMA this past trip, just a couple of weeks ago. He's seen Indiana Jones at least 3 times, so i thought it was a no brainer. When I asked him (we could only do one because of the times of the shows and everything else we HAD to do), he did not hesitate at all and said "Indiana Jones". He said that after seeing all the promos on LMA, he still would rather Indiana. So that's what we did, and he and my mom (first timer) LOVED IJ.
With the age of your sons, though, I would go with LMA. Cars, motorcycls, jet skis...just sounds like action they would love.