Personally, I don't think there's any competition.
The Touch Pro is a great device and feature rich. Yes I have experienced some reception issues but nothing major. The build quality is good but I can't compare to a Diamond. I had a slight issue regarding the sensitivity (lack of) of the buttons on the face but I think it's just a case of gettng used it and finding the optimum place to press.
The user interfaces is great. I really hope HTC continue down this path even when WinMo 7 comes out. By this I mean their skinning/rewriting of things is a good thing. I just wish they had done this a more/to more apps such as the inbox/messaging application, calculator, all system messages/dialogues, possibly even the PIM apps like tasks, calendar etc.
But this is a great device and I really like it. Best device (both WinMo and in general) experience I've had out of the box by miles I think.