As for who has the best mantis....
A mantis is a mantis.
QED.
What is mantis kung fu? It is, well, kung fu that looks "mantiddy." Whose looks the most "mantiddy"? I don't know. Whose has the most effective "mantiddiness"? I have no idea. Can you hit? Can you trap? Can you block/redirect? Can you do these things utilizing the proper methods of motion?
If you can, you're doing mantis.
Which of these two guys is doing better mantis?
http://www.youtube.com/watch?v=8E9uLaMBevg
http://www.youtube.com/watch?NR=1&v=ODreYYme0rs
Both pretty ****ed good, but the forms are different. Principles of movement are the same, and both are better than I am....but I'm not a mantis specialist.
Still doesn't explain if either guy can "fight".....since that depends on many more factors than how a form looks, the principles it teaches, or even the length of training. All of that depends on circumstances. I've seen amazing BJJ guys get tapped out by people they "should have" beaten.