I don't think there is a "best". A lot depends upon your budget and intended use for the rifle.
The RWS 34 is a pretty decent gun for the money. I have one myself. The RWS 358 and 48 are true magnum airguns, but they're more expensive than the 34. The highest velocity guns are usually heavier, harder to cock, jump around more, and often not as accurate as some of the lower velocity air guns.
