I certainly think that there are different approaches to take with this question. If we are looking at who experiences more of the emotional range that defines "heroism," Odysseus might receive the nod because he experiences the life led during war and afterwards. It is in both conditions that the reader sees Odysseus experience consciousness and there is a fuller understanding of this in his experiences in the Iliad and in The Odyssey. If the "better" hero is defined in the more tragic condition, Achilles probably is more tragic than Odysseus. The very fact that he recognizes in the Iiiad his own tragic condition and succumbs to it is what makes him the "better" hero on the level of tragedy, a fact confirmed in his conversations with Odysseus in the underworld in The Odyssey. The idea of "better" probably needs some level of qualification because both characters represent much in way of heroic figures. The strength and pure intensity of Achilles is equal to the guile and brains of Odysseus. Their favoring by the Gods with either Zeus or Athena is also representative of how both are very much similar. Yet, the term "better" is going to be clarified a bit more in terms of providing an answer in a satisfactory manner.