BG is pretty good. I tried it back in the day and Snick got diarreah from it. I like Merrick as a company but then I heard there was some shenanigans going on so who knows. I did want to tell you that BG has three flavors (chicken, salmon, & buffalo) but they are all chicken based with added meats to creat flavors. That was one part I didn't like about it.
Some other good grainfree kibbles I like and recommend are:
Instinct by Nature's Variety
Orijen
Acana
Innova Evo by Natura
Fromm Surf & Turf
For some reason or another I have heard things about all other companies which make me nervous. Either recalls, or being packaged in less than ok conditions, etc. In the end I think what works for your dog is best, but it takes FOREVER to figure that out
-Vivian