The speaker here is Antinoos himself: whoever succeeds in marrying Penelope, he says, would surely qualify as ‘the best of the Achaeans’. As the narrative will make clear, however, Antinoos is the least worthy of all the suitors in pursuit of this double goal of marrying Penelope and thus qualifying as ‘the best of the Achaeans’. See also the comments at O.11.179, O.15.521–522, and O.16.076.