Out of your list I would go for the XS25 tuned. The Ruger branded springer I tried was the worst POS pellet rifle I have ever shot.
Random dumb thought here but why not just convert the Prowler from a gas ram to a spring. Not sure what all would be involved but you wanna tear down and tinker, maybe go that route instead??
The XS-25 SFB is $85 on Flying Dragon Air Rifles. You could also get a fixed barrel XS46U for $140.http://flyingdragonairrifles.org/index.php?route=product/category&path=59Thanks,I have since sold it, but the xs-25 I got from Mike at Flying Dragon was too notch. Taso
Gonna tinker with the prowler today and see what I can do, it's the only airguns I haven't taken apart yet, mostly because I haven't felt the need to, nothing to really lube or shim and it shoots like it's supposed to already. Maybe I can put a little lube around some key frictions points and make the cocking stroke feel better. It does have a slight sticking feel to it near the bottom of the stroke and sounds dry. A .177 barrel would be nice to have for it as well as a .22 barrel for the XS28M so I can shoot cheap ammo and not blow through all the pricier .25 cal pellets I have to mail order.