Tilapia is one of the highest protein foods per ounce. Has a ton of good nutrients but can be high in Omega 6 fatty acids. Sadly it is my least favorite fish.
Salmon can lose a lot of its benefits when farm raised in a shallow commercial setting. I am certain it is served at much more than just Applebee's. There are precursors that help (such as Atlantic salmon) but if a restaurant wants to be shady they can still claim their salmon to be Atlantic salmon, even though the water is never deeper than 5'.
I have yet to find Tilapia that I like.
Fish is a weird thing. There is a lot of encoded language with fish. Atlantic Salmon actually refers to farmed salmon, and the geography of it is irrelevant. You can farm Atlantic Salmon in Washington State, which... why would you do that???
But there are common names that we generally think refer to a single species of fish, but can be any of dozens of actual fish. Rockfish is a catch-all name, as is Sea Bass. If you order one of these on a menu, it's really a crap shoot. Scallops are another one, where you may think you're eating a scallop, but are actually eating some kind of stingray or other fish that's just been cut to shape with a cookie cutter.
Regarding farmed fish, the way they're farmed absolutely makes a difference. Done on the cheap, and they will have a lot of contaminants that just aren't good to eat. Just like other farmed meats. You can get chicken that is full of antibiotics and hormones... or pay a little more to get chicken that does not have those things. You can get responsibly raised beef, pork, and poultry, or you can pay less and get lower quality meat from bargain basement, corporate farms.
A lot of places view Atlantic Salmon as a renewable resource, and it can be. But it is a fact that what makes wild caught so healthy is the life it has led. If you ever have real, wild caught sockeye or chinook salmon from the PNW or Alaska, it is a deep red, oily meat that doesn't smell or taste "fishy." Atlantic salmon is actually dyed pink so that it looks like salmon, but it lacks the heavy omega oils that make wild caught salmon so healthy.
Real salmon is delicious with just salt, pepper, and a little butter. Or you can cold smoke it. It's also served often in sushi restaurants raw as sashimi. And if it's wild caught salmon, if you sear the skin and get it nice and crispy, it is sooooo good.
As my 12 year old would say, "I stan wild-caught salmon."