I've had the Invos and they are by far my favorite tire.
Quiet, grip well, and last a good amount. I would definitely buy them again for my next set once my current tires wear out.
I've never had the Ventus V12's but I've heard good reviews and a few friends who have them swear that they're awesome tires. I'm considering them as my next set if I don't go with the Invos.