The best one to get right now is the Vepr square back... Normal versions will have a slanted Reciever in the back where the stock meets with it... These versions also have proprietary mags. The square back takes normal AK mags and normal AKM stocks, but retains the rpk's style bulged trunnions and barrel... You can get them from Atlantic Firearms.
Arsenal's are known to be well made too, but there was what they called bubble gate... Where if you mag dumped one too many mags, the paint started to bubble.... These are very expensive...WASRS are acceptable as are kit builds from reliable sources. WBP Rogow kits are also good if the builder is a known good builder. (They have both cast and forged trunnions, most rather have the forged, but the cast WBP's have held up no problems)
If all American is what you want, I think DDI is at the top spot...they are brand new and all the important parts are hammer forged. (The only one in America) the frosting on the cake is that their bolts are so precise that they are said to be interchangeable... Rob ski tested I think ten bolts in his test gun and they all headspaced properly! (That's huge in the akm world... Only one in the world) the bad side of DDI, is that they had an issue with their extractors in the first batch. Robs rifle went through two extractors and he sent the rifle back... DDI is very active over on the files and appears to have gotten on top of the extractor issue quickly... Even sent out replacements to any customers that wanted one.
PSA also has a gen 2 PSAK... It uses a forged billet trunnion, but appears to be a cheaper alternative to the DDI for the American guys... They usually get sold out pretty quick too.
I would have a hard time choosing between the Vepr square back and the DDI myself... The Vepr is a combloc rpk of very high and proven quality... The DDI is everything an American Company should be, but did have slight teething issues.
Atlantic has the best selection of AK's in my opinion... When you get a chance you can browse through their stock, just stay away from RAS47 and IO (unless the IO is an Archer)