The B-25 from "Adventures in Airguns" iis a clone of the RWS 34. If it's tuned by Mike Melick it's no doubt a fine shooter.
The B26-2 from "Best Airguns" is a clone of the Beeman R-9. If you buy it from them you can check the box and have it sent to Mike and he'll check the internals and make sure it's working properly so you know you'll get a gun that shoots good, but I don't think he does a full tune on it.
I guess strictly from a cost perspective the B-25 is cheaper, plus it's fully tuned. You could also check with MM and see how much extra it would cost to do a full tune on the B26-2. The RWS 34 and Beeman R-9 are both really nice guns and these rifles are pretty much exact copies of them so I don't think you can go wrong with either one. Personally I like the B26-2 better and would opt to get one of them and have MM do a full tune on it while he had it. I have 2 B26-2's and I absolutely love the thumb hole stocks on them and the R-9 Rekord trigger clone. I also have a Ruger Blackhawk (same gun as the B-25) and I love that gun as well. Guess it depends on what your friend prefers...
Oh yeah, BTW... if your friend goes with the B26-2 have him opt for the "low comb" model. The "high comb" stock presents some scope mounting issues as far as proper eye relief.
As for the Blackhawk from Pyramydair....... I would rather go with one of the other 2 since Mike Melick will have his hand on both before you get them.....
Jeff