In reply to h.cook2000:
Whatever is cheapest! It'll only last you a couple of years but by then you'll have a better idea of what you want to spend your money on...
I picked up a 70m Beal Yugi 10.2mm from V12 Outdoor a while ago. It was on sale for ~£69, then add my 15% Premier discount... bargain whichever way you look at it
Dry treatment may protect the rope, but I never use a single rope in the wet - I don't sport climb in the rain and it is rarely raining indoors... Trad/winter climbing it is much more worth it IMO.
If you are going to use it outdoors (for sport) I would get a 60m, but you can probably get away with a 50m 80% of the time on sport? (just make sure the end is tied to something!) 60m folded will also give you 30m 'halves' for trad if you are desperate although proper halves are much better.