1515, 1Y or 1515, 1.5D?

I'll running it with MM controler, i know, probably have cogging but want to give it a try, and if the MM blow, i'll ordre an TMM 16018.

But just don't know if i'll take the 1Y or 1.5D

1Y with 14t pinion have same speed that the 1.5D with 18 pinion, and i've this 2 pinion here, so wich one wil give me the better runtime and smoothest ride.