Final Fantasy VI
Was the first FF where I felt the story was actually great. Memorable characters, the Esper system was a precursor to 7's material system. Favorite villain of the series with Kafka. Memorable moments such as walking to Marsh with he overworked theme, Cyan's family departing on the phantom train, Celes' attempted suicide, and the three stage boss battle with Kefka. Best soundtrack of the series. The world of ruin with Celes was a nice change of pace to go along with Terra and the world of balance.
Final Fantasy Tactics
Most mature FF story at the time. Unlimited replay value due to the deep job system. Dedicated PC modding community to have new campaigns/characters. Some cold ass dialogue from Delita. The assault on Riovannes Castle and the events during and after that section one of the most memorable moments for me. Lots of secret characters and weapons to discover in the non modded vanilla game. the unique changing of grid placement in each level+different enemies makes grinding more fun than the previous FF's.
Diablo II/Lord of Destruction
Addicting dungeon looter that is the grandaddy of the genre. any dungeon looter today can find traces back to D2. Memorable environments such as the forests near the rogue encampment, the deserts outside of Lut Gholein, the Tundra of Mount Arreat, etc. Memorable bosses such as Andariel, The Summoner, and Baal. Lots of skill tree/armor combos to make fun characters. There's great mods that tweak the gameplay and environments too to give the game more life after you get tired of the vanilla one.
Halo:Combat Evolved
Finally got a well playing console shooter that controlled smooth as butter. Had a variety of environments and semi open ended levels. The Flood reveal on 343 Guilty Spark is still one of the most memorable gaming moments for me. Second half of the campaign has more of a horror tone to it. Great use of color palette and art design that makes characters, weapons, and textures look great, even today. Top notch voice acting from people such as Jen Taylor. Multiplayer is still fun, and I prefer its "less is more" approach to the sandbox. Maps weren't built with balanced MLG in mind, resulting in some will and wacky maps like Chiron and Boarding Action that you don't see in later Halos. great soundtrack with songs like the Main Theme, Covenant Dance, A Walk Through the Woods, and Under the Cover of Night. The PC version brought us custom edition, full of brand new campaigns, new maps, weapons, n more that's still active today.
Pokemon Crystal Version
Might be the biggest generation to generation upgrade we've seen in the series. Gen 2 added animated sprites, cell phone, radio, day and night cycle, Pokemon eggs, EVs/IVs, 2 new types(steel and dark), held items, berry trees, fully colored characters and environments, 100 well designed Pokemon that didn't clash with gen 1(shoutout to my guy cyndaquil), more secrets than the previous gen, more balanced gameplay(psychics no longer broken), a savings account, memorable soundtrack(Red battle, Ecruteak City, dragons den) and you got to travel back to Kanto after beating the Elite 4, which was a shock to kids everywhere. Cherry on top was the games ending is you fighting yourself from Green/Red/Blue/Yellow.