The choice of breed is one of the first decisions that needs to be made. A breed cannot be changed so choose carefully. An engineer needs high nano skills in MM, MC and TS mainly to be able to get more powerful robots. Therefore you should not play an Atrox, since their Intelligence and nano skills are poor. Intelligence is important because it is a 80% base ability of many nano skills. A Nanomage works well for an engineer; they have better nano skills and intelligence. An Opifex or Solitus will also work, their intelligence and nano skills are average.