PM me if you have specific questions.
The AK market has gone significantly downhill with the popularity of the AR platform, but there are still a couple of decent builders. However, sources of quality aftermarket products (i.e. rails, stocks, barrels, etc.) will pale in comparison to those available for the AR. Same goes for ammo.
I’m assuming you’re looking for 7.62x39? This is the most popular and easy to find. 5.45x39 is another great choice, but that brand of ammo is becoming more scarce.
I used to own a Romanian AK (WASR-10), but sold it many years ago. Ended up buying a Sig-556R (7.62x39, and takes AK mags). A much higher quality platform, basically a “Swiss AK.” Very happy with it.
However, if you are looking for a traditional AK, I would look at the designs sold by Arsenal. Very good quality for the money.
If you’re going all in and want a custom build, check out Rifle Dynamics (Jim Fuller’s company out in Vegas). Be aware, the wait time is very long. Also, Krebs Customs does some cool AK after-market work.
Stay away from anything by Century Arms. Very poor quality control, with the nickname “Drunken monkies” by people in the industry.
For quality aftermarket products, I’d recommend anything by Midwest Industries. They do great rails for optics mounting. Avoid anything by Tapco. Cheap, and will end up in the garbage can at some point.
An AK’s accuracy will surprise you if good ammo is used. Try to avoid that cheap shit (i.e. Wolf, Tulammo, etc.), unless you just want to do plinking at the gravel pit. Some of these powders are highly corrosive, so make sure to clean the barrel thoroughly after each use.
Best of luck.