You missed out 'both', Sunshine. <G>
I really couldn't choose between them since it's the combination of both their talents and the way that they work together as a team that makes Lois and Clark work for me, and I've never been more than passing interested in anything they've done outside the show.
Now, if we're talking purely on a 'who is most attractive and sexy' basis - well, has to be Dean of course.
LabRat