The only reason you want to un-crate for profit is for unusuals, salvaged crates, and the special holiday crates. All ususuals are worth more than a key, so are most (probably all) salvaged crate stranges. The holiday crate items don't start with a high price, but they usualy skyrocket after a few months. Look at festives. If you want specific items from crates, it is better to sell the keys for metal, or trade the keys directly for the items you want.
It all depends on what you are looking for. If you want profit, uncrating is not good. If you want to have the thrill of luck, then uncrating is good for you. But, usually profit is not gained from uncrating.
Random crafting though, can be much more profitable than uncrating. If you buy two 1 ref hats, and craft them and get a Double Cross Comm (super rare hat), you can resell for a massive profit. But, there are a limited amount of "rare" hats, so it is not too easy to make profit. BUT, if you time it right as a new hat comes out, you can craft for a craft # item which can be from 1-3 keys to 1-3 Buds, depending on the number and the hat.
The same as above applies to random weapon crafts, but random weapon crafts is much more profitable, becuase there are less weapons. You just get a Class Token (for a class that has a rare weapon), a Slot Token (matching the same slot as the rare weapon), and a scrap, and craft them together. Some rare weapons are worth 1.33-2 ref, depending on the weapon and how new it is.