Ken's has a great selection of food. The only real down side i see is that most things you get from there comes in a HUGE amount. Most things are 1/2 lb minimum. Doesnt sound like much, but 1/2 lb of flakes for instance is a bag the size of a normal piece of paper, but atleast an inch thick, if not more. Realistically, 4 different kinds of food would be 10 lifetimes worth of food for most hobbyists.
A few years back I was in the same boat as you, I wanted to try some of the foods but knew it was WAY more than i could use. So I started selling "samples" here on the forum and other places. That way i could have a selection and offer other members a more reasonable and useable amount. It was very popular and i did well with it. I stopped and another member started doing it, but slightly different. Its been awhile since ive seen any posts from them, not sure if they're still at it or not.
But, anyway, if you wanted to order something anyway, you could wrap up most and freeze it, it will last much longer that way. Or split an order with a friends or whatever. My top 2 recommendations would be decapped brine shrimp eggs and the appropriate sized Golden Pearls. Never met a fish yet that wouldnt devour those, as quick as they could get them in their mouths (unless they were just too big to be bothered by such small offerings).
My next choice might be the meat wafer with spurlina. The more aggressive eaters would attack it, causing a little cloud of particles to spread out and the more shy fish would get them. If you want to see all the fish in your tank, more or less in one place, this will do it. And they seemed to stay stable in the water for quite some time. And if one wafer was too much you can always break an appropriate sized piece off to feed.
After that, I dont know, there are a ton of different choices. I was always a fan of earthworm based foods, just cuz I know they're super nutritious for fish. But again, there are a ton of good choices...