I would say from my experience and experience of others that carrying a lot of fuel for the fire (more than you think you need) is more important than carrying a lot of firestarters.

Carrying different firestarters and backups is smart, no doubt about that. But if I were to choose (for example because of the weight/space limit) between these two options:
3 firestarters plus small amount of fuel vs. 1 reliable firestarter plus lots of fuel I would pick the second one.
In reality this won't probably happen since I carry backups but I try to keep the firestarters somewhat small and make room for more fuel (tinder, kindling) instead.

When I got StrikeForce I thought how great it was - massive rod, big sparks, good for working with gloves on etc. but soon I realized that a middle sized version of "Swedish firesteel" type firestarter would still get the job done, would save a lot of weight and room that could be used for more fuel.

Of course I might change my opinion on this in the future and change my firestarters size/weight:fuel size/weight ratio based on another experience but now I think that more fuel is the better option.
It also depends on the weather, season of the year etc.