Its difficult to choose between the Airsporter and Mercury 'S' variants but in my opinion the Mercury just takes the lead as Im not a lover of the tap loading rifle as I prefer direct barrel feed. The Mercury S is one of the better British break barrel rifles IMO and on a par with the Omega and () Longbow.
All the above, of course, dont hold a candle to a nice HW35 or a tuned 'Sport.
ATB
Ian