You'll get better low light condition footage w/ the sony pd 170. The Cannon gl2 is not as good but the footage from both in lighted conditions are roughly the same. If you are wanting better and looking to spend over 5K than look at some HD cameras which I don't have enough knowledge of them to guide you there.

You'll spend plenty for a pd 170 once you get eveything you need for it 4-5K I would say.

Good luck