as I and most folks will say here "wear what you like" its very hard to identify a tartan and most people can only identify a small handful by memory. so by wearing a tartan that is not yours, most regular people wouldn't even give you a second glance or ask if you if you "belong to a certain clan". so where what you like whether its based on colors or some other reason. i know that a lot of people might take it as a sign of respect if you wear their family colors. so go ahead and pick the pretty one!