Sojourn said:
The ANH voice always sounded harsher to me -- not in a more realistic way, but in a poorer-recording-quality kind of way. I personally prefer the fullness and richness of the ESB and ROTJ Vader voice, but that's just my taste.
I prefer the ANH voice, but I'm a big fan of consistency and it's lot easier to change all the lines in one film rather than two, so I'd vote for tweaking ANH.