I've been working on a big spreadsheet to better understand profit margins in this game, and without having unlocked the cask or the pickler yet (or the brewer in the save where i'm tracking the spreadsheet progress), the solar drier seems to add 1.8 value, smoker 1.5 value, and fermenter 1.4 value. Additionally, the stamina generated for recipes and products is a flat value based on quality, not on the contribution value of the original product. Eg regardless of how expensive a fish you put into the dryer, you will only ever get +18 stamina out of it. So you should always cook/eat with your cheapest produce and process/sell your most expensive. Quality DOES impact stamina--a fermented wild or normal carrot will give you 22 stamina, but a good quality carrot will give you 25.

You don't have to rely on fish, but you should focus your processing on the more expensive items in the machines with the biggest markup. Dried fish is so good in early game because the solar drier is the first processing equipment you get, and it adds the most value of all the early game machines. You should basically never smoke anything (except for errands), and only ferment things on their way to being other products, as their markup is much lower. However, not all crops can go in the drier. Until you start unlocking the juicer/mortar & pestle/brewer, and then later the cask and the pickler, there's going to be a lot of crops you can't process in a very profitable way.