For me it depends on the game.

For MBr, I have it set to Extra Ball, as getting the special is a skill thing (for collecting 3 instruments).
For WH20, I have it set to Replay, because the only Special is off of the random (Mystery Canyon) award.
Foe EBD, I have it set to Replay, because there are so many Specials possible, that I'd have way too many Extra Balls.

I'd prefer it if you could set it to a number of points that would be worthwhile (i.e. worth making an effort to obtain), but usually the "points" setting is some value like 10,000 (making it a waste of time).

Well, you don't get a "bunch", you get one (I guess that could be considered a small bunch).

And since the Special is only collected on an out-lane, it's really more like a kickback. Yes, you get an extra ball, but you have to lose the current ball to get it.

My complaint with this, is that usually the "points" award for a Special is so low as to be effectively meaningless. When a good score is in the billions, awarding like 50,000 points for a Special is just silly - I'd rather have the audible knock.