NT05's are really good in the rain, especially with those two huge center grooves (same reason why SS are good in the rain), I've had no issues with mine in the rain. Like Epstein said the NT05's have a slight advantage in over all grip but slightly less in rain/comfort. Its a trade off I was willing to make. They seem to wear really well compared to RT615's and they are not nearly as loud though they're not super quiet either.

Star Spec is the best DD tire made.
NT05 is a better street/track tire imo and cheaper than everything else.

Honestly I dont think you'll notice too much of a difference between the two when using them as front tires for drifting. They'll offer pretty much the same grip.

Nitto came out with an NT05R which is a drag radial so dont confuse the two.