The gun appears to be a member of the basic Nitro Piston family of B19 Chinese rifles so the stock from any other member of that family should be a fit. Personally I like the look of the Nitro Venom but depending on personal taste you have choices up to and including the Benjamin Regal or pretty much anything in between. If your trigger guard is part of the stock of course you'd need to order one of them as well. The trigger guard for the Regal is metal, the one for the Nitro Venom is plastic. Don't forget screws and perhaps the attachment bolt between your stock of choice and the action - they can vary in length. You absolutely can not use the stock from an NP2, NPSS, or NPXL. Those guns have larger diameter compression tubes and will not fit.
FWIW, I have the Nitro Piston Vantage (wood stock). I too like the look and feel of wood, but on the advice of some on here, I swapped it out for a Nitro Venom and it shoots much better. Also added a CDT trigger. Changed all the screws to metric allen head bolts. I have given some thought to soft bedding the wood stock to see if that helps? Good luck!