and of course you have to ask yourself whether you are a " traditionalist" or a "Modernist" and that will decide an important question...
BTW the Royal Stewart is the Universal one that anyone can wear,as a Subject of HM the Queen, usually you have to be a member of or descendant of the Clan to wear a clan tartan!! It is the most Comfortable Formal Outfit I have EVER worn in my life...!!!!!!!!