I haven't seen Inland Empire yet. I discovered David Lynch in the last 5 years and it's taking me a lot of time to get through his movies because it takes a whole lot of processing to really understand every one of them. It creeps into your psyche and sometimes your dreams. And for me it takes time to muster up the energy to put myself through another one of those experiences.
Eraserhead was a trip, I still haven't totally figured it out. But in terms of pure cinematic enjoyment Blue Velvet would be my favorite.
Now that I hear other Lynch fans talk about Inland Empire I'm really excited to watch it.