The actor John Hurt once told me this was the "contemporary" play he most admired, and my belief is that among many respected thespians he was far fom alone in this opinion. While my own favourite is Stoppard's "Arcadia", and have never seen "Godot" on the stage - only televised - the typical Beckettian abstract nature of the dialogue is certainly one that appeals to me, and, having read it in book form, also, I would have to rate it among my highest preferences, as theatre.
What I have only recently discovered - and which considerably alters my perspective of the piece to further positivity, and provides me with a greater sense of understanding (not that "understanding" is necessarily a feature Beckett himself would have wished to promote!) - is the fact that he wrote it originally in French! "En attendant Godot" retains a greater subtlety in the title alone, since, in English, we tend to atomate the connection between the words "Godot" and "God", which, while perhaps implied as a theme, doesn't require being rammed down our throats with such immediacy. Or is it Beckett's quiet joke, reserved for Brits, to watch us rush to draw the conclusion? Whatever the case, having been sent to a Franco/Swiss boarding school, at seven, for health reasons, and consequently spending 23 years of my life as a resident of La Belle France, a French version is now on my radar screen for future investigation!