Ocelot was/is my favorite villain character throughout the series. I think one of the things that made him so great though later on, and this will be controversial, was that you never exactly knew how much of him you were going to get. So you savored every scene he was being foreboding, confident, and poised in.
Really sad to see they went with anyone else besides Patric Zimmerman. He's probably my second favorite VO in the series, besides Snake.
Shout out to Paul Eiding for his work as Campbell, but especially his work in MGS 2. The guy gives one of the greatest performances in the series, making subtle changes to alter his voice into sounding more staccato and robotic compared to MGS1, but not in a ham-fisted or blatant manner. Only after you finished the story and went back (and compared it to MGS1 as well) to listen to dialogue more closely did you realize there was something off about him all along.