Manga Studio is pretty nice imo since you get a lot of the stuff that leads people to use SAI(line correction and the likes with inking pen) but is also much more familiar to use than SAI in my opinion thanks to an interface much closer to Photoshops' in Manga Studio 5.
Link
Kai
I really like your line style. If I could get to that point with digital art, I'd be happy.
What program do you use, if I may ask?