I've built AR's, FAL's, a M1, a 1903A3 and a PSL and numerous AK's from kits and the AK was not bad. Takes a little more time than the AR or FAL but with the right tools it's pretty easy. Doing good rivets is the hardest part but easy once you get the hang of it. I also like the MAK-90's.There are good Romys, good Yugos and good Century built guns also, but it would be best to shoot them first.
I'd choose a Yugo last. Norincos are good.
I've built AR's, FAL's but wouldn't try an AK.