im going to say haltech p1000 is a better unit, but i have the aem series one in my own car and i am very happy with it, does everything i need.
for me i want the best product at the best price, so at the end of the day the aem is cheaper to aquire and thats the only reason i went with it over the p1000, i got it cheaper and it does just about everything the p1000 does