I chose Romanians, Greeks and other South Slavs. It really is purely geographically based when it comes to race of Bulgarians.

I would say they look really like blend of Southern and Northern Europeans, and one sees it going case by case also, lighter phenotypes = original Slavic, darker phenotypes = Greek and Balkan natives (Thracians) prior to Slavic arrival.

Maybe also some Pontid Ukrainians could also pass as Bulgarians, but my personal experience of Ukrainians is most are like most Russians, Belarussians and Poles in looks, though some Pontid and Balkan types appear in Northern Slavic populations also.

They say Bulgars were Mongoloid Turkic tribe, but I see nothing Mongoloid in this pictures, so obviously they had only cultural impact (name of nation and state) and not genetic. If they were Iranic, as some claim, then indeed they might have left trace, but nothing Mongoloid.