From his farewell to his wife Andromache in Book VI to the splendid description of his funeral with the which the epic concludes, Hector exhibits many of the hallmarks of the archetypal protagonist of a modern novel or comedy: he has a legitimate, productive relationship with Andromache, in contrast to that of Paris and Helen; his fatal engagement with Achilles despite knowing the foregone conclusion is one of many incidents that attest to his immense courage and bravery; even the rashness that characterises his slights of wise Polydamas' augury are redeemed by penitent reflections such as:
"Shall proud Polydamas before the gate
Proclaim, his counsels are obey’d too late,
Which timely follow’d but the former night,
What numbers had been saved by Hector’s flight?
That wise advice rejected with disdain,
I feel my folly in my people slain.
Alexander Pope (1715). The Iliad of Homer, Book XVIII.
On the other hand, the epic begins with "Achilles' rage", and indeed rage, sulk, and sorrow all but sum up the emotions that animate Achilles' acts throughout, at times to such an extent as to incur divine displeasure. At other times, it is largely his sheer proficiency in warfare and the entreaties of Thetis that recommend him to the gods.
Yet it appears to me that in designating a principal character considered in terms of importance to the story, let alone merit, Achilles is usually preferred to Hector. The Wikipedia article on the Iliad, for example, contains no mention of Hector in its introduction. The film Troy could perhaps serve as an example.
Rather than attempting to encompass every opinion ever expressed about the subject, the answer should reference a few arbitrarily chosen examples written by well-known authors, such as may be expressed in discussions of the characters in prefaces to translations, or in (parts of) poems that may be entitled An Ode to Hector, etc.