We face many options when designing a system that automatically generates prosody from linguistic and paralinguistic information. The literature provides several candidate phonetic models, phonological models and mapping tools to actually implement the system. We detail here some dimensions along which these models have to be compared. We show also that systems employing quite similar phonetic models can still have radically different approaches. We present results of a first evaluation comparing two systems using a superpositional model of melody on a common multilingual prosodic database of spoken math formulae. We conclude that prosodic models and intonation theories could certainly benefit from well-defined tasks and fair benchmarks.