Tough question brother. I really like the Mexican stuff I had done in the past, but my all time favorites are probably the Thai crosses. Hard to beat the spices you get from those, but they can never be released in to the public because of their inner sexing properties.
Honestly using pure sativas in the past has been a pain in the ass and long frustrating work. I have some hybrids I did using SSH that are nice when one shows up, but again they are so all over the place you really have to be looking for that diamond in the rough and the average consumer wants nothing to do with things like that.
I'm working right now on a new Skunky strain, but so far not had the best results.
Keeping it real, I'm just not focused on pure Sativas ATM. Not a lot of interest in the USA.