Not trying to do a top ten, because it's too hard, but:
You have to have a classic Webley. Because: reasons. For me, toss-up between a nice Senior and an early Premier or something like an early straight-grip target.
Generic 'sporting" springers: BSA Scorpion. Diana model 5/LP5. Diana LP5M. HW45. Near miss: Competa Indian.
CO2 single shots: almost any (the Crosman/Benji/Sheridan guns are all a bit the same and share the same poor grip/trigger/sights issues).
CO2 non-replicas: Crosman 600. And those Drulov "semi auto" things.
CO2 replicas: CP88. And 5/686.
SSP non-match: HW40. Honourable mentions: Nemesis, HW75.
SSP match: FAS604. Honourable mentions: Air Match, Baikal 64, Daisy 717/747/787.
Match springers: FWB 65, 80. Diana 10. Honourable mention: Diana 6/6G/6M.
PCP: no idea, don't do that. Harper Wolf? Daystate?
Junk: all IGI Gun Toys (RO71,72, etc). G10. Gats. Etc.
I picked up a Webley nemesis the other day (GB made!) and after a clean up and lube, it’s running rather nicely. Not the most powerful air pistol out there, but a real joy to shoot!
'Windage & Elevation, Miss. Langdon - Windage & Elevation!'