From an engineering stand point .......rivets are best because they are the most predictable and have little to no impact on the base metals being used. They are also easy to teach people how to use. Gas welding is just a thing they teach in Aircraft Mac. School and is kind of an ego thing. It also dose not require much money to set up for it. IE..a torch with welding tips and bottles. It's just my opinion but TIG is the best and is the hardest to master. It's used exclusively in the Nuclear Industry so that should have some merit. Dave