That's going to be a tough one.
Alot of the answer depends on what you consider as a top-fire joystick game.
There are games like Battlezone that use two sticks, one of which needs a fire button.
Then there's games like Tron, that originally used a trigger stick, but could use a top-fire.
Then there's games like Xenophobe, that had three buttons on the trigger stick, but could as easily use three buttons on the CP.
Cloak and Dagger originally used two Wico sticks, with a separate button on the CP for lighting the fuse on the bombs, but it works nicer with a top-fire.
You might also want to use the stick as a shifter for driving games, in which case you may want to have a top-fire to use as a nitro button.
I don't happen to care for the true top-fire sticks because they put your hand in a weird position while playing.
I play most of the games that require a button on the stick with trigger sticks because they are more comfortable for prolonged firing.