well as most will tell you here...just keep testing until one just knocks your socks off. A signature scent, imo, is one that not only smells great and one that you adore, but also one that people will remember you by. I for one, at the moment dont have one because i interchange to often...though if i had an endless supply of Chanel Egoiste, it would likely be it.
My advice is to look for something that not only you will enjoy greatly, but that is memorable to your wife and those around you.
Burberry Brit and Touch as well as Platinum Egoiste all sound good to me! I like them all very much.
My current girlfriend like Egoiste(regular) and L'Homme by ysl on me...so she remembers me by these two scents in particular.....i hope this has helped a little...but, by the way, you should also try Acqua di parma colonia and assoluta...these are great and also classics!