Vucic has got this, with or without second round. Unfortunately so, I might add, because I'm not a big fan of the SNS/HDZ/GERB type of Balkan center-right party, who often pretend to be patriotic folksy conservatives while leading their countries straight into the EU just to line their pockets. Corrupt as hell, and only in it for themselves. Then again, it's not as if most opposition parties are any better.
As for Vucic being a former radical, this is true, but it seems that when money talks Aleksandar Vucic listens. During the refugee crisis in 2015 he criticized Orbán and his fence and stated that Serbia would be willing to take in refugees, which, according to Vucic, makes it "more European" than "some of its neighbors" (maek u thnk). I bet most SNS voters would disagree with this stance.
Seselj or bust imo. Always love it when Serbian candidates have a history in the city of peace and justice