ORIGINAL: digital_trucker
Graupner props. They pull very well and rarely break upon abuse (I can REALLY testify to the abuse part). Despite their toughness, they're rigid and don't deform, which is why they pull so well. They're the only props I've used that perform as well as the old Top Flite Super M and Cox greys.
I like the Graupner props too, just wish they had a few more options, like a 5.5x4 prop.