My two cents on your question:
I have been lucky enough to try both. My preference is Animal Pump and here are a few reasons why:
Stim Control: If lifting in the evening, (2-4 Hours before bed) you can remove the red pill to minimize your stims. Shock is a powder, which does not allow you this option. Its do or die, with less sleep for someone like myself.
Pump: Shock gives me a better overall pump then Pump. However I noticed it was a sometimes painful pump that limited my range of motion on some days. Some may like this, but I like the suttle "let you know your getting a pump" that Animal Pump gives you.
Energy: Overall energy for both are GREAT, however, with Shock I get the "stim crash". Pump is a nice suttle energy, that is ready about 30 min after consumption, yet powers you through your workout, and brings you down slowly. I crashed, each time I used Shock.
As with anything else, it is individually specific. You may not have a need for stim control, you may not be stim sensitive, you may want painful pumps. I will say this, price per serving is definitely in Shocks favor. However I prefer to pay a little more for a product that works for ME!