I've used Royal Gold and BioBizz coco. They both seem excellent products to me. Gold Label also seems high quality. And my hydro shop gave me a free "sample" full-size bag of General Hydoponic's CocoTek coco, which from what I've read is likely good quality [with GH apparently promoting a new coco-specific line of base nutrients and this CocoTek brand coco].
Manufacturing/distribution location (shipping costs) and company source are also something to consider. For example, if you're on the West Coast, US, you can probably get a better deal, if only on shipping, buying say Royal Gold or something else made regionally. BioBizz is made in The Netherlands and presumably a better buy (vs. a US brand) if you're in Europe. You might consider whether you want to go with a US or EU product vs. coco processed in Asia. Personally, I'd stick with a product made in the US or EU, and/or at least coming from a product line/brand known as being of overall good quality. Also, products with organic designations, such as OMRI, are likely to be of good quality.
I suspect by now, like anything, if you stick with your favorite or other trusted brand and do some basic Internet checking (problem products will be readily spottable), you'll almost certainly have a good outcome.
I'm sure there are exceptions, but I'd keep away from buying bricks.