I used Gleim as well. There is a lot of discussion on this in the CMA strings if you do a little searching. Some people don't seem to like it as much but I went 2 for 2 in the same window (got that discount, ya!) so I can't complain at all..
I have not been a fan of Becker at all for anything so I personally would not head in that direction. I think Wiley has the “official” study materials of the CMA, or they did last time I checked and have heard a couple good things about them. I would shoot for Gleim or Wiley, with the note that Gleim is WAY cheaper…or it was last I checked. Good luck!