Doesn’t matter what sort – other than –
Look for a big zip pull you can grab with gloves, soft collar liner, velcro wrist tabs and most important of all pit-zips. Pit-zips really reduce the boil-in-the-bag effect. A front pocket that you can use without taking your camelbak off is good (the camelbak belt strap fouls most side pockets). Oh – and check how small a space it will stuff into when not being worn.
Buy exotica-miracle-breathing material if you like – but remember it’ll stop breathing when its covered with mud. Whatever it’s made of – don’t put it in washing machines – you’ll bugger up the proofing and seam sealing.
