Hi Shahak.

A lot of the becker students passed the exam by just using becker's study materials. I passed BEC with just becker. However, I failed FAR once, so I borrowed Wiley materials to practice more. Surprisely, I've seen a lot of questions show up in both Wiley and Becker's MCQs. I like Wiley's explanation on the answers because it is explained in more detail. But I don't like to read wiley's books because sometimes they can go way too deep. (I feel like wasting my time to read them) 

So my suggestion is: if you've already use Becker, stick with it. If you feel like you need to practice more, then just buy MCQs not the books from Wiley.  Good luck