What Pacecar said, although the difference is usually minimal. So it's basicly how you prefer to collect. Myself,I like OGP.
Your answer might depend on why you are asking the question. If you are looking to buy the set, it might be wisest to choose the raw set. You see, while I agree that the graded sets can sell for more than the raw sets on ebay, that doesn't really mean they are worth more. It just means there are people out there willing to pay for them. You need to understand that virtually all sets sent in to NGC or PCGS are going to be graded either 69 or 70. So even if the set is raw, it's still a 69 or a 70 in just about every case. So you have nothing to lose by buying a raw set, and you might even gain should you ever decide to send it in and it comes back 70.
but you forgot that if the set is not in the original shipping box, only the RP and the S mint mark will recieve the "25th anniversary set" label,UNLESS NGC or PCGS changed their policy for this label