Veronika is more curvy, it's a sign of a lot of sexual power. On the other side Natalia's body looks more compact an tight to me.
So my vote is...
Round 1: Veronica will start strong, winning the first round and having Natalia shocked.
Round 2: Natalia's firmer boobs will dominate Veronica's bigger pair. Now Veronika will be shocked seeing her pride making way for Natalia's better pair.
Round 3: The 69 round should be very even, I can't predict a winner here.
Round 4: During the tribbing round Natalia's more compact body will overpower Veronica's, shattering her hopes.
Round 5: After beeing defeated in the tribbing round Veronica will be without hope, knowing Natalia's stronger thights will ravage her pussy by pushing the dildo deep inside her until she can't take any more. So Natalia will also win this round in dominating fashion, stripping the title away from the current champ.