Green tank question!

[Malianna]

Hi there!
I know it might be ill advised from all the advice I see here, but I'm just really stubborn when it comes to wanting to play tanks in games.
Will I be at a serious detriment if I started playing a tank on day 1? Granted I'm sure its not as bad as I think, since I'll be picking between a shadowknight and paladin.

If it is, am I just better off at maining a druid or necromancer till then?