Well, I'm bound to say it: the Mk1/11 Airsporter.

1) The best looking springer ever. (Beats the prosport in my view for balanced looks.)
2) Solid British engineering
3) One of the safest loading mechanisms ever.
4) Very quick loading courtesy of the auto tap.
5) The gun we all lusted after - before the Germans invaded the British market.
6) No plastic bits.
etc.
etc.
etc.

I like the Sport but it has been over-hyped on here and in consequence is usually over-priced as well.