It all depends on something you do later

[hider=Spoilers]When your in the ice city before heading for the last dungeon. People will come to the door wait til it says Kratos and you'll talk with him. Instead of fighting the three angels you'll fight Zelos and have Kratos in stead of him for the rest of the game.[/hider]

I'd prefer Zelos (haven't actually played the game just watched a full playthrough) he can combo better. also he is more relatable.