Okay, to get things going - locks for me are
Ballybunion Old
Lahinch
Prestwick
Royal St Georges
Rye
Sunny Old
TOC
Sean you magnificent bastard! This is such an interesting list -- are you sure it's 'greatest' rather than 'favo(u)rite'? For many 'normal' people would see this and call it favourite.
To paraphrase Kerry Packer, there's a little bit of the ranker in all of us, gentlemen. And so, to show Steve L I am not a total crackpot, or I should say I am a wanker 23.50 hrs daily and a ranker 00.10, here go my locks:
Ganton -- always always Ganton. The cheese stands alone.
WH Old -- the more I consider my rounds on this course the more I think it underappreciated (don't know where it's ranked so not commenting on whether it should be ranked, is underranked, etc).
St G Hill -- although I hate that like Sunny Old it has a life preserver hole. Embarrassing.
Woking -- I refuse to allow my love of this course get in the way of its clear-eyed excellence.
Rye -- but for the 11th one of the world's truly tippy top courses, not just links.