I have never had a better screen protector then the one I got from PPCTechs... I have Invisishield on the back of my Touch, and I know the screen protector is better...
For the Pro I would order the Crystal Clear version...
http://www.ppctechs.com/HTC-Touch-Di...hoose_unit.htm
However I am not sure a screen protector for the pro or diamond is necessary, the screen is very scratch resistant from what I understand... Real glass vs plastic maybe?