In reply to John Aisthorpe:
This is quite an interesting question and I think everyone probably has a different answer, as it largely comes down to fit.
Personally I've always found Scarpa/La Sportiva to work best for me, as both of the brands seem to make a big deal of the sculpture and design in/around the heel - there's a feeling of craftsmanship when you pick them up and look at them. That said, I'm specifically referencing some of their more technical shoes (e.g. Instinct, Skwama, Otaki, Solution), so maybe some of their other models (Vapour V for example) have a more relaxed fit in order to make them more comfortable. That said, I don't believe you need to wear a painful shoe in order to heel hook effectively - it's just about finding the right thing for you.
On the flip-side of the above, I also have a pair of Anasazi VSs kicking around for the odd occasion where their unique - and distinctly un-heel shaped heel (!!) - fits where nothing else does. I think these removed a grade or two from
Lay-By Arete (f7B+) at Slipstones, as such always worth packing just in case!
As such, (and as someone has just said) go to a shop and try a load on. If they've got a wall there then give them a go too, as any forum chat or shop talk is largely redundant compared to actually using them.
Good luck!