For me their smell is quite different, they share their construction in some way. Egoiste is more about the rose for my nose and Le 3º Homme more about jasmine and carnation.
Both have great sillage and are longlasting, but i prefer the Third Man by a long shot. Egoiste is likely to get more votes here and it may be easier to wear (not for me anyway) but I feel Le 3º Homme more unique and classy (against actual Egoiste, don't know the vintage cologne concentree version).
If you love both smell i would tell you to choose Le 3º Homme...it's at least as good and it's cheaper too!