Regarding calibers, the 38-55 is the most desirable as far as collector's value goes. If you reload, I would recommend a 38-55. Modern factory ammo is a joke, far less powerful than the standard HV 38-55 factory ammo sold for most of the 1900's, which put a 255 grain bullet out the barrel at 1,600 fps. I reload my own and find that 1,500 fps is plenty to give complete penetration on deer.
With regard to collectable, make sure the wood has never been sanded (wood should be at least flush with the metal and preferably proud of the metal) and make sure it has never been re-blued. Either will pretty much wipe out the collectors value, although they would still have shooters value and nostalgic value.
If you do not reload, then the 30-30 is your best choice (early Winchesters were marked '30 WCF', which is the same as '30-30'.
Regarding rarity, for the 38-55, saddle ring carbines are hardest to find and rifles much easier to find. It is the opposite for the 30-30. Both are great calibers; I own and reload for both.