This paper augments Boehm-Turner's model of agile and plan-based software development augmented with an AI search algorithm. The AI search finds the key factors that predict for the success of agile or traditional plan-based software developments. According to our simulations and AI search algorithm: (1) in no case did agile methods perform worse than plan-based approaches; (2) in some cases, agile performed best. Hence, we recommend that the default development practice for organizations be an agile method. The simplicity of this style of analysis begs the question: why is so much time wasted on evidence-less debates on software process when a simple combination of simulation plus automatic search can mature the dialog much faster?