I like the Weapon Comparison Tool by jjflanigan. I used it for a similar Dwarven Axe vs Scimitar comparison and it matched my own Excel calculations. It calculates Damage per Swing, which is a useful reference point.
Results:
Heavy Pick is slightly better (~2% up to a target AC of 41. D-Axe is moderately better (~10%) on AC 44+.
Assumptions based on this build:
16 BAB
+20 STR (EDIT: should be +15)
+5 Weapon
+2 Crit Rage
+4 GH
+2 Axe Enhancements (12AP)
PA enabled
Improved Critical
More To Hit favors the H-Pick
More Damage favors the H-Pick
Seeker favors the H-Pick
Elemental Damage favors the D-Axe
Notes:
The H-Pick user has 12AP to spend on something else.