I've never used Stresscoat myself, so I really can't offer an opinion about it.
I have used MelaFix and PimaFix. They are both great products for treating minor scrapes, bumps, and cuts. I like to think of them as the aquarist's equivalent of Neosporin. They are also good preventative medicines - if you are netting fish and transferring them to another tank, a dose of Melafix/PimaFix will help prevent those inevitable scrapes from becoming infected. They are certainly products that I would keep in my fish medicine chest.
Trouble is, the manufacturer and alot of aquarists sometimes overhype the product's capabilities. Just as you wouldn't waste time applying Neosporin to a third degree burn, you shouldn't bother using MelaFix/PimaFix for columnaris or advanced finrot. In those cases, go with bigger ammunition like Fungus Clear or Maracyn.