Who is better among all of them

And I don't want babies crying over my fixitation on Kanu Nwankwo .If you know you won't give a mature response,please dust your feet,clean your mouth and quietly leave

Comparing all these players could be quite complex because they are different sets of players.
You could have grouped them like this:
Adebayor V Kanu (both have many things in common: tall, leggy,almost same style): I go with Kanu
Kanu V Okocha(both are skilful): I go with Okocha
Utaka V Yakubu(both forwards, though style quite dissimilar): I go with Yakubu
Adebayor V Yakubu( Both premiership respected forward): I go with Adebayor

If at all I want to answer your question of comparing the four together, then the criteria has to be who is/was most effective in his chosen role, then I will rank them like this:
1, Okocha
2, Kanu
3, Adebayor
4, Yakubu
5, Utaka

and I will like to add:
Utaka V Ogbuke V Uche V Osaze: Who is our best winger?