Its got to be the original. I really like Revelations and how it returns to the slower paced gameplay of the older games but I just like everything the original did - bosses, enemies, puzzles, funny yet terrible dialogue (plus REmake took all that, added even more and brushed up the gameplay and visuals considerably)
Haven't played the Resident Evil Revelations yet as it only came out less than a week + no cash on me at the moment so I can't give you a opinion! But I still think the original is still the best & Resi Evil 2 is a close second!
i am dying to play Revelations, havent yet so cannot comment. RE4 is in my opinion the greatest game ever made and if any of the new ones come even close to that then they get my vote. Although that said, RE5 was a total travesty and I held picketed protests because of this, and they wouldn't respond to my letters thelling them to start all over again and deliver me a better game, damn them.
Neither imo stand out, the first one improved on Alone In The Dark in every way and was pretty groundbreaking, but the controls still let it down, the rest for me havent made me buy back into the series ever since.