I like the quality of the BRS reactor the best for GFO and it can be split for also carbon. It really is made of top quality of materials. However, it is bulky ( size of standard RO/DI canister ) and the negative for me, is it is too heavy to hang on the sump.
However, it works great and Bulk Reef supply support is the best.
A new feature I like a lot, is that on the Bulk Reef web site, they have added new videos that help you set up equipment. For instance, on GFO, you want the flow to be low, so media does not break down.