In reply to Anhibian:
Length, climbing moves and /or quality pitches, line and remoteness and/or scenery for me!
3* climbs for me have been:
central grooves, SCnL- Glen Coe
Shangh-High, eastern rampart Beinn Eighe.
Fiddler’s Nose, sgurr an fhiddlear
The sea the sea, Atlantic wall, Slioch
War and Peace, #4 buttress CnL NC
Central Buttress, triple buttress Beinn Eighe
Supersleuth, Mainreachan buttress Fuar Tholl.
I realise most of those are at the highest end of my grade and snowed-up rock routes. I suspect my experience of them and of ticking them has made me very biased toward those. Struggling to think of a V that’s achieved the same wow factor:
I particularly liked things like
Savage slit, #4 CnL NC
Crest Route, SCnL Glen Coe
Purple Blaze, beinn an lochain, arrochar
recess route, north peak, Cobbler
There are others I am sure