The "best" as in "most accurate" air pistols and rifles are those used in Olympic events---but be prepared to spend serious $$$.
Think Anschutz, Steyr, FWB (Feinwerkbau), Morini, Walther, Pardini, etc. See ChampChoice.com , Pilkguns.com, 10pt9.com, and Targettalk.org for an introduction to...