If you watch Alton Brown's show Good Eats (Food Network) he frequently uses 3D models to show where various cuts come from. A good example is the episode "Tender is the Loin", where he uses a model of a steer to show where the loin primal is and then location of the tenderloins.
I think that your problem doesn't come from using the wrong cut, but from using the wrong quality tier of meat.
The cheapest pork in the supermarket, no matter which cut, is produced from cheap mass-held pigs with a certain type of "lifestyle" - no movement opportunities, cheap feed, lots of antibiotica. It produces a certain kind of meat, known as PSE meat, which stands for "pale, soft, exudative". The last word means exactly what you describe: a meat which loses lots of water during cooking. So no, you cannot get more "bang for the buck" by changing the cut.
I still assume that you are getting a better price per gram cooked meat from buying cheap meat and cooking it down than from buying expensive meat which will lose less water, so I guess that, if price is the most important part for you, you shouldn't change anything.
Another word about quality: the S in PSE is also your enemy when making goulash. Generally, you want lots of collagen in goulash, and some fat for taste. PSE meat has almost none of them. The old idea that cheap meat is best for goulash comes from times where the difference in meat prices was based on the cut: a shoulder cost less than a filet, and that was it. Nowadays, this connection still holds for the same animal, but if you look at the different price tiers, the cheapest meat, especially in pork, is not at well suited for long and slow cooking methods. If you buy cheap meat, the best you can do with it is usually mini-steaks or schnitzel, heavily dressed to make up for the lack of taste.
Best Answer
I don't believe they are inversely proportional. You can a tender cut that has a lot of flavor, such as a good rib-eye steak.
For flavor, the general rule of thumb is "fat is flavor". Were not talking about all the thick and hard gristle fat on the edges, but the marbled fat speckled in the meat. That fat helps provide flavor and moisture as it breaks down.
For toughness, it relates to where on the animal the cut is taken from. Meat taken from areas where there is alot of muscle activity and movement is going to be "tougher" and required the more low and slow cooking approach to break everything down. Meat taken from the opposite side of the spectrum that gets very little physical activity is going to be softer and more tender.
At the end of the day, you have to cook the cut of meat properly. You can make a tender cut tough and a juicy cut dry if you don't cook it right.