primary what?
Yeah, ....primary for what? The thread immediately went the SD/HD tactical end of the world direction and I suppose that was the OP's intent anyhow. But.....
If we are talking one rifle to do many things, a general purpose rifle that can serve in all the confrontational roles one can imagine, perhaps compete in some practical rifle event or informal bullseye competition, hunt any game on the continent, and shoot frequently enough to keep ones marksmanship up, the AK comes up a just a wee bit short in my estimation. Hey, I've got nothing against Kalashnikov's rifle and really like the 7.62x39mm cartridge, however.....
The x39mm cartridge is not the deal it used to be and lacks a bit of range and punch when considering a wide variety of targets. Some AK's do not take an optic easily (mine for example, no rail). While the AK's trigger serves well enough for what originally was a full auto design intended to build a base of fire against an adversary, it pales when compared to even a price point sporter these days and a good trigger is important in shooting well, especially at any distance. So...
I can't imagine not having a good .22lr, an adult rifle with good trigger, decent sights or optic and reliable as a brick. But I wouldn't want to fight for my life with one, or be forced to hunt medium or large game. A fella really needs minimally two rifles in my opinion.....a good .22 and some type of GP centerfire, which conveniently brings us back to the start of the thread.
So if I could keep my .22, I'd opt for a .308 bolt carbine of some variety. I'd want the option for a flush mount or extended mag. I'd want a pic rail up top, to put a modest scope on it, say a 2-7x32mm, or perhaps one of the newer 1-6x30mm numbers with an illuminated aiming point. I wouldn't disdain some type of magnifying red dot, provided it would be one unit and not a separate magnifier. I would want some provision for back up iron sights just because stuff breaks.