I am looking to pick up some brass 7.62 x 39.

Is ammo marked "reloadable" better quality than non-reloadable ammo?

Primers are either of berdan(generally not reloaded) or boxer(easily reloaded) types.

Brass 7.62 x 39 with a boxer primer will be more valuable then the berdan primed stuff because it can be reloaded.

What makes the ammo more "accurate" is consistency in powder weight, case wall thickness, trim length, bullet weight, bullet seating depth, primer seating depth, primer ignition consistency, and finally your gun and what it likes. Generally, most match grade ammunition will have boxer primers and be reloadable.

So in short, yes, I suppose "reloadable" ammunition would be of better quality.

Some of the finest ammunition in the world has been Berdan primed.  The level of effort and attention to detail used in making ammunition has nothing to do with which of the two primary types of primer are use.  And Berdan primed brass CAN be reloaded-it's just not nearly as easy for several reasons (including availability of the right primers).

From a US reloader's standpoint, as stated above, Boxer primed brass 7.62X39 cases themselves would be "more valuable," but that doesn't mean that these rounds were necessarily better to start with.

Pretty much what this guy said.  Some of the finest mil-spec 7.62x51 I've shot (Swede and Hirt) has been Berdan primed.  

Figure out what your rifle likes, then balance out your decision with:
Do you reload?
If not, will you police up your brass and sell/trade it to someone who does to recoup some of your initial cost?

If you answered "no" to both, Berdan Primed (i.e. non-reloadable) might be a better buy for you.

I don't know. Are you going to reload the x39? I mean, maybe for a hunting round, ok, then it would matter, but I don't know of very many people that reload for it. Not saying you can't, but just wondering why you would.