Difficult for me to answer this myself as I just about like them all. Bulgarian ones are kind of my favorite in that they seemed to be a little more asthetically pleasing and have shot better for me in the accuracy department. This being said a friend recently got one of the Saiga reworks from Arsenal USA, and it is a sweet shooting, and sweet looking AK.
The Chinese MAK 90's work like, well like an AK is supposed to. They kind of grow on you too. The much maligned WASR's even work good when properly set up. I have about 3000 rounds thru one with out a malfuntion.
Yugo AK's are nice and seem to be well put togather as well the M70 shoots good too. Then there are the Other caliber AK's like the 223, 545, 308, and some others as well. What are ya'lls thoughts on what you like and why.
Have only had experience with 2 -- WASR and the MAK90. Of the 2 I like the MAK90. It looks and feels like a well made AK - the WASR on the other hand, feels "cheap" -- BUT will digest anything you put through it!!!!!!