I agree, I think Mark is a fantastic commentator for all the reasons you outline above. I also like his voice, which I find clear, easy to understand and easy on the ear.Literally anyone is better than US commentators... but nobody comes close to Mark Hanretty. He's knowledgeable, positive, extremely exciting, and yet relatable and able to let out a giggle once in awhile that doesn't sound unprofessional, but rather like someone who is just tickled by the amazing performance he has seen. I don't think I've ever heard a commentator as good as him and I've been watching for 35 years or more.
Belinda's voice is the reason I don't enjoy her commentating - I find it really monotonous and grating (sorry, Belinda)
I can't whistle either. Something to do with palate shape, I'm told.)

(Or as my mother used to say, "Wait, I need to put my glasses on...now, what did you say again?")