Well, Warcraft III should be on everyone's list here. Why else would you come to this site?
My
favorite games:
Half-Life 1 and 2 (keep an eye on the Black Mesa mod if you like these).
Warcraft III (check my sig for a custom campaign

).
Age of Empires I and II.
Jak 2.
Ratchet and Clank: Going Commando.
Pokemon Red/Blue and Gold/Silver.
The Darkness (amazing game, bashed by critics because its online is shit).
Final Fantasy Tactics (any fan of tactical games should play this).
Heroes of Might and Magic III (still gotta play the King's Bounty remake, which should be just as good).
Fire Emblem: The Sacred Stones (same as for FFT).
The last game I played, Enslaved: Odyssey to the West, is amazing as well. If you like games that focus on story, get this one. The mix of platforming, scouting and fighting is really good as well (though the combat system isn't very deep).
My
least favorite games are the usual sports games, Wii shovelware, music games, most movie games, etc.