Always been happy with the Samyang 14/2.8 even though it was a bit de-centered, but for that kind of money I'm not gonna complain. Plus the effects where minimal on normal viewing sizes (1440 at the moment) and I don't do a lot of pixel peeping (more concerned with capturing the moment instead of how the pixels look).
But with the arrival of the new Voigtlander 15/4.5 E I've made my choice, perfect balance between size, optical performance, metal built quality and features like an aperture ring, CPU, hard infinity stop and the option for a filter.
Downside is that they don't come in a Nikon mount, maybe Nikon will surprise us at the Photokina with a FX mirrorless camera
Voigtlander 15/4.5 LTM, Voigtlander 15/4.5 E and Samyang 14/2.8 AE (with adapter rings so bare lens is smaller when used on Nikon F)