AEM is one of the best out there, with the exception of maybe Motec. Motec is definitely big $$$$, especially with their CDI, wideband, etc. You even have to pay for their tech support by the hour (they usually include a certain amount of hours when you purchase a unit), unlike AEM.

UTEC is not a stand alone. The last Haltech I saw had the worst interface I've ever fucking seen!