1. Bullfrog
2. Psygnosis
3. Maxis
4. Nintendo
5. Squaresoft
So yeah, I only started gaming in 1995, so only for a select few developers do I ever go back and try out their older stuff. These five, however (particularly Bullfrog and Psygnosis) I make a special effort to try all of their games and they remain a large amount of fun even today.