The Gemara Sukkah (37b) writes
ואמר רבה לולב בימין ואתרוג בשמאל מ"ט הני תלתא מצות והאי חדא מצוה א"ל ר' ירמיה לר' זריקא מאי טעם לא מברכינן אלא על נטילת לולב הואיל וגבוה מכולן ולגבהיה לאתרוג ולבריך א"ל הואיל ובמינו גבוה מכול - And Rabba said: One takes the lulav bound with the other two species in the right hand and the etrog in the left. The Gemara explains: What is the reason for that arrangement? These species constitute three mitzvot, and this etrog is only one mitzva. One accords deference to the greater number of mitzvot by taking the three species in the right hand. Rabbi Yirmeya said to Rabbi Zerika: What is the reason that we recite the blessing only with the formula: About taking the lulav, with no mention of the other species? Rabbi Zerika said to him: Since it is highest of them all and the most conspicuous, the other species are subsumed under it. Rabbi Yirmeya asks: And if that is the only reason, let him lift the etrog higher than the lulav and recite the blessing mentioning it. Rabbi Zerika said to him that he meant: Since the tree of its species is the tallest of them all, it is the most prominent, and therefore it is appropriate for the formula of the blessing to emphasize the lulav.
Though previous questions noted height as the reason for our focus on the lulav in the bracha "Al Netilas Lulav," my question is why Chazal say height is the tie-breaker at all (rather than another form of importance like beauty or fragrance)?