Which is better for street fuel tuning (using A/F ratio and EGT guages to tune), with larger than stock injectors and better fuel pump? The Apexi S-AFC, HKS AFR, or an Additional Injector Controller?

 

The Apexi' S-AFC has work well for me.

 

None of them should be tuned with using A/F ratio and EGT guages! I know people will disagree, but these devices are supposed to be used to acurately tune the fuel flow to the engines requirements. The best way to do this is on a dyno with a wide-band O2 sensor. You'll maximise power while ensuring no lean-outs. An hour on a dyno is a whole lot cheaper than a rebuild.
BTW, the AIC controls additional injectors (hence the name!), not the ECU controlled ones.

 

Is a dyno the best way to tune the S-AFC? Sure it is, but a A/F gauge and an egt gauge can do a sufficient job, untill such time as a dyno run becomes a reality.