There is probably not a good answer to this question, because there are so many factors that will bring out the phenotypic expression of high or low productivity in any one of the species or cultvars of the genus capsicum. That being said, your standard cayennes, habaneros, orange/red bhuts, nagas, ajis (pineapple or lemon), 7 pots (Douglah, Yellow, Brainstrain... etc), and scorpions (ButchT and yellow IME) all fruit pretty heavily in my experience.