There are so many crpg games that have been released that are beyond belief. Most responses are going to be similar, and those games are good. However, the five or so titles that keep popping up are not the end-all, be-all of great games. Think of it like movies.. if you ask a forum of people to name the movies to watch you'd get countless Star Wars, Godfathers and the occasion Hitch****. Other classics like The Maltese Falcon and The Tin Drum you probably wouldn't hear, but these oft-forgotten classics would be required viewing for an understanding of cinema.
Darklands - My number one recommendation for anyone who asks. An epic historical rpg that came out over 10 years ago. I cannot use words to describe.. just play it! You'll be glad you did.
The Magic Candle - Fabulous game that gets a blank stare from most people nowadays. Fun battles, good puzzles, non-linear gameplay, truckload of quests, and an absolutely huge world = fun times. The two direct sequel are pretty decent.. with the MC series, the box art is inversely proportinate to the enjoyment.
Shin Megami Tensei - Dragon Warrior, Final Fantasy and Phantasy Star are all well and good, but Atlus' post-apocalyptic, heretical Megami Tensei series is an absolute must even for people who hate jrpgs. Since the two Shin titles on the SNES have been translated into english, there are no more excuses for not trying these out.
Buck Rogers: Matrix Cubed - Another non-Tolkienesque crpg that takes place in the 25th century. Forget the corny show and serials, this game is much more serious than stupid, wise-cracking,"bidee-bidee-bidee-bidee" robots. Political intrigue, assasinations and betrayal are glued together with the combat from the SSI AD&D games.
Realms of Arkania - Very intricate series of RPGs designed by Guido Henkel who helped produce Planescape: Torment. At first glance, the games may appear to be somewhat run-of-the-mill (generic fantasy setting, standard story, etc.). Not is all that it seems. Lots of stats, awesome story and fun combat make this series a keeper.
Thats all I can think of off the top of my hat. Have fun.