I have heard that sinking pellets are better for fish as it is a more natural way to feed. As a side note I also heard that floating pellets are thought to contribute to swim bladder issues in some fish, an interesting thought i.m.o.
I've yet to see that be true of any fish I've ever kept, this includes years of keeping Cyphotilapia, a fish that some have been told shouldn't ingest air due to being a deep water fish. The logic of the gulping air bugaboo is flawed. If 'gulping air' was the issue some make it out to be for some species, you couldn't net them from the tank to transfer them to a bag, bucket, or another tank, you couldn't take them out to strip eggs or fry or to measure them without risk, yet some of the same people who claim floating foods and gulping air are a danger do these other things without giving it a thought. Catch and release for fisherman would be a sham, and the same for biologists who might catch, measure, weigh, take scale or fin samples for DNA analysis, then tag for tracking before releasing them back to the water. Stress from handling is one thing, but the gulping air theory is flawed logic.
I've fed both floating and sinking pellets over the years, I prefer sinking, but have fed a lot of both, and I've fed a lot of freeze dried shrimps, etc., which also float. No problems at all from floating foods. Not only that, even with the sinking pellets I feed, some of my fish, including some of the Cyphotilapia are up at the surface 'gulping air' as soon as I open the lid and going after pellets as soon as they hit the water. No problems, nothing.
Don't know what other people are doing who think they're getting swim bladder issues (or conditions that mimic swim bladder issues) from floating foods, but potential causes are overly cool water, injury, infection, or wrong ingredients in their foods. A number of aquaculture studies have shown some plant based ingredients, like soybean meal (and some other forms of soy) can cause intestinal inflammation in fish, and certain combinations can do the same, like soy and peas. (Species differ in the levels of such ingredients they can tolerate.)