What's today's most accurate production retail calculator?

[Steve Simpkin]

Well... For what its worth, you can see a relative figure of merit for "accuracy" using a specific metric [ arcsin (arccos (arctan (tan (cos (sin (9) ) ) ) ) ) ] at Calculator Forensics.
The results table is shown at :
http://www.rskey.org/~mwsebastian/miscprj/models.htm

Oddly enough the only production HP models to achieve a perfect result of 9 (with 10 digit resolution) are the Kinpo made HP-9S and HP-30s models which where not designed by HP at all.