There is only one way: try by yourself and see results.
You can obtain some informations reading scans posted here in the forum, but "best" burning speed is related to three factors:
Burner, firmware and batch of media. For benq burners, moreover, there are also other factors: WOPC, SB and OS. Then there are so much variables involved that it's impossible to answer to this question.
I suggest you to read threads dedicated to scans, make decisions on what media you can buy (not all media are available anywhere), and then do some tests.
Being factors involved so much is very difficult to state general rules. Also people with the same burner can obtain different results with the same media.