I have been using Ken's Fish pellets and flakes for about 4 years. I love them (because my fish love them and do well on them).
I keep 3 types of his "Ultra" flake foods: Spirulina, Earthworm and Multiworm. I also keep ~10 different types of his pellets. I rotate what I feed, and complement with frozen food, earthworms, insects, veggies, Nori, and Repashy. I also finely grind several of the different pellets, and mix them with flakes. This I consider an excellent 'community food', which is one of the rotating items.
I have also used Ken's Metronidazole flakes (in fact, currently in use with some new fish in QT).
Altogether I consider Kens foods as of very good quality, particularly when rotated with fresh foods. The prices are very favorable (particularly in the mid- to larger size packages). I keep my stock refrigerated or frozen, except for small amounts for regular use.
I have thought of starting a thread about this before, because I have been somewhat surprised that not more people seem to use these foods, or at least they are less frequently mentioned in threads, versus other brands. For me, excellent! Yes, some of the pellets are quite hard, such as the black soldier ant pellets, but then again, silver dollars love to chew!
I will add that Ken's Fish also have extremely good prices on a wide variety of dry goods. For filter replacement parts, I have found no better. And around black friday last year, I bought 2 Aquaclear 110 from them, after extensive shopping and price comparisons (couldnt be beat!). And no, I am not affiliated with them, nor receive any benefit from speaking highly of their business.