IMO it just depends. Do you want caffeine/stims? Go Alphamine. Want pretty much no-stim (keeping in mind Synephrine is a stim but won't be very stimulating unless paired with caffeine)? Go Shift.
The new Shift formula is very impressive IMO. It would be my choice out of the two for a recomp, but can't really go wrong with either when combined with the proper nutritional and training approaches for the goal.