I still say more Nord in recent statues but come to think of it, in Oblivion, he does look more Breton.
Notice the statues in skyrim look nordic because for some reasons the nords really want to believe Tiber was a nord.
Myes, I think Talos, I mean Tiber Septim, I mean Hjalti Early-Beard was a Breton who, as the Acturian Heresy dictates, was confused with Ysmir (Wulfharth), who was just -very- clever with hiding the truth, thus making him seem... shall we say godlike?
I think it was more because the greybeards named Tiber "Ysmir, the dragon of the north." Thats why people tend to get confused by it.