I also have both and not sure which I prefer. It's like which one of your children do you like the most?
Having said that, it does depend on which manufacturer of each gun you are referring to. I had a Yugo SKS with a very nice trigger, but all the grenade stuff on the end of the barrel was kind of too much. The gas valve was something that required a lot more care and feeding than I cared to give.
(put it away dirty and you'll spend quite a while just taking it apart in order to clean it, next time you shoot)
I have a Chinese now I like better in most respects, but the trigger needs to be tricked out to match the one I had in the Yugo. The Chinese is shorter and has a chrome lined barrel the Yugo's don't have.
My AK is a WASR. the overall shorter length and reduced weight adds to the versatility of it compared to most SKS's, plus it also has the chrome lined barrel. The WASR's come U.S. compliant with the Tapco trigger which puts every SKS trigger I've ever used to shame.
The stock SKS lacks a lot of the cool factor of the AK, including the pistol grip.
These are just my opinions, of course, your mileage may vary.