I know stackexchange frowns on "suggest this software" questions that can be subjective, but I do believe there is a correct answer (non-subjective) to this question.
I have to render for speed and quality and can (for these particular projects) do without the excessive control that cycles offers.
I've seen Luxrender and this if I am not mistaken is much slower than cycles. Mitsuba might be faster, but I read it has some limitations.
Which of these renderers can give speed and quality even if some sacrifices must be made?