For PC, I would have to say: Xwing vs Tie Fighter.. played the hell outta that game.
There was also another game, set underwater, allowed you to manouver in a complete 360 degree environment... the name of it escapes me though.
For Console, I would have to say initially Shinning Force II for Sega Genesis or FFIV for Super Nintento. To much fun delving into these RPG's.