On a singing front, they all can sing. But I judge them all by how well they sing Defying Gravity and Rachel not only consistently hit the big notes, she equalled and quite often out sung Idina's studio version (ie, the original version) and made me believe it every single word every single time.
So, yes, my favourite is Rachel because ultimately she brought something new to the role with outstanding vocals.
Liked your analysis but feel its crazy that anyone should feel they have to justify their opinion. Surely thats the whole point of a forum? To be able to express one's opinions!
On the 'Rachel' front, thought you might be interested in checking out my youtube page (Lou Lee) as I've been editing and creating a London cast recording featuring Rachel's incredible vocals.