I've used NO xplode and Jack3d. Both are good, but I do find that NO xplode gets me going more -faster workouts, less fatigue and the ability to easily keep going even though the workout is over.
That said, when I was on NO I was also using it less consistently (about 3 times per week - non-consecutive) and so everytime I took a scoop (I've never done more than one scoop) it was like... boom.
Have heard great things about Animal Pump and have a container but just havn't cracked it open yet.