I have not seen too much of the Nightmare just yet, but having thrown the Aura of late I can definitely give it the thumbs up.  I have never seen a Brunswick solid finish as strong as this one for me.  So far I've got LOTS of miss room.

Both of these are good balls for what you want to do.  This is how I would approach it.

If you are speed dominant with lower revs, then go with the Nightmare.  The cover/core are stronger than the Aura and it will help compensate for the higher speed by reading the breakpoint consistently.  Plus this ball is clean up front for a high performance piece, so it will store energy well.

If you are low to medium speed with lower revs, then go with the Aura.  It still has a ton of hook and with the lower rev rate, it will easily be effective.  Also, it is very clean up front (more than the Nightmare), so it will store energy really well to help carry the corners.

Have to agree with Tommyboy. The Nightmare will be better if you are speed dominent. If you are leaning towards the Aura... go ahead. It takes surface changes great and still gets through the fronts with no problem. Thats whats so great with this ball. It will still get through the fronts even when sanded down. Either way you go... you will not be dissapointed. Both are great balls!!