I used the factory canopy latch. I drilled a hole through it for a padlock, which will allow me to lock the latch so it can't be opened. I will NEVER put a lock in it and I am often tempted to order a new C-607 latch handle so I can get rid of the stupid hole. Here's why...
If someone wants to steal my avionics and the canopy is unlocked, he will open the canopy, steal the avionics, and be on his way. My insurance company will buy me new avionics and I will go flying. I might even get a panel upgrade out of the deal.
If the canopy is locked, the thief will break the canopy, steal the avionics, and be on his way. My insurance company will send me money for new avionics and the cost of the parts to build the canopy. I will then spend A YEAR building a new canopy, buy new avionics, and finally go flying if I can still stomach it after that nightmare.
I built one canopy. That's enough for one lifetime.
If you're going to lock something, go with the gas caps.