Im not able to give my experience ive tried about 3 different ones...currently taking super advanced NOS...a guy at the gym takes only arginine and swears it works. Makes sense, but not a chemist.
Hard to say. I think the best pump comes from good diet and taking advantage of your body's insulin. A GDA like Need 2 Slin is good for this.
A lot of people see good pump from agmatine. I personally don't see anything with it.
Also could look at Creatine Nitrate.