ah, the never ending struggle to find the perfect keyboard.
I agree with all your points as what makes for a bad keyboard, plus I have a bigger issue that I grew up using a Spanish layout keyboard, so finding the perfect keyboard takes double effort.
I specially like gaming-grade keyboards like the Razer Lycosa and the G-15 but those only come in English layout, which more than messing with Spanish punctuation, kills my right hand by moving the and key from the bottom left of the keyboard and also moves the semicolon one row up.
My current favorite is the Samsung Pleomax PKC-700B which is like a perfect classic layout keyboard. (except for the oversized return key, which makes the right brace key to move next to a tiny backspace key)