Always fun to see this sort of disagreement about what I guess are generally numbers 75 - 125 in most GB rankings... I think I like both Broadstone and Delamere more than Sean does, but the one inland course which in rating terms continues to puzzle me a bit is Hankley Common. A lovely place for a game, but one of the top half-dozen venues inland in the UK? Really? Better and more interesting than Alwoodley or Hollinwell?
My really heretical rating thoughts on GCA are, I guess, Dornoch, but I have only ever played two rounds there so doubtless have much to learn and to some extent Pennard, where I have played a bit more and where I had the marmite view thereof within Wales confirmed again only the other day, talking to some participants in the recent Welsh Open Seniors champs there.
Underrated nowadays, emphatically (although not on this site) remains RND Westward Ho! with as Ran says about the greatest variety of hazard of any golf course in the UK.