As a very basic stock for a basic "general use" knock-about rifle, the ones they come with will be decent. One thing to know ahead of time though, is that at least mine had very sharp edges in some places where the supporting hand goes (meaning the top outer edge of the stock where it meets either the receiver, the top guard, or the cocking handle/action bar). I just used a good file and smoothed it all out. And it's served me well enough for now.
Thing is, I've discovered I really like wood stocks, and so I got a USGI wood, then a Boyds wood, and followed it all with a USGI fibreglass.
The Norc polymer stock isn't any bulkier than a M1A or M-14 wood stock. Grip on the USGI 'glass is a little thinner, but not by all that much.