I haven't quite reached my second year of fishkeeping yet, but here's
my two cents:

I've had very bad results with Tetra products in general and flakes,
specifically, especially lots of floating problems. I switched to the
Hikari pellets--they are the mini floating type as I couldn't find the
sinking variety, though they can be presoaked so that they will sink.
My fish never get floaty anymore, and now I rarely have to serve them
peas to "clean them out," whereas before I switched foods I had to
serve peas a few times a week!

I also feed the SF Bay Fish Gumdrops, which go over very well, though
I often wonder if one "gumdrop" for two medium-sized goldfish is too
much. Still, my water is stable and the fish seem happy. I purchased
both types of food at the evil Petco, but I am sure it's available
elsewhere.