A cider yeast, or (and it may be the same thing) a champagne yeast
But anything works, they just give subtly different flavours, even bread yeast (but the difference may not be so subtle and may not be quite what you want)
I've tried Munton's Gold ale yeast and it gave perhaps a slightly fuller rounder flavour. A couple of wine yeasts I tried gave a slightly funkier flavour (Gervin D, I think was one of them)
Champagne or cider yeast but be careful with some packet cider yeasts they are full of artificial sweetners.
However if you want a west country style cider and encourage Malolactic fermentation the you are best culturing up a bottle of old Rosie yeast see here