I rethought my answer, and I think it is better to apply in the case of EFL. For a L2 speaker accuracy does comes upon fluency on daily communication to avoid the unconvieniences caused by misunderstanding. However, my idea was that learners should not be afraid to speak in class (with/without mistakes). As long as you speak, your faulty English will be assimilated by the correct ones.
I assume you mean grammatical accuracy. In this case, I would choose fluency over accuracy. For a L2 speaker, they have the linguisitc environment, so they know little about English. The problem for them to study English are lack of vocabulary and making mistakes in grammar. They know some simple words, that's enough for communication. What's hard is to get them talk!!!!