I have a number of aluminum boats. All but one are riveted. Dating from the late 40's to 2017, I have had good service from all, but also take good care of them. For my applications, which is mostly east of the Mississippi and both fresh and salt water, riveted works fine. If I had my 'druthers, I suppose I'd take welded, but could happily survive with just the riveted.
That said, if you are dealing with big water and where hulls get pounded, the welded will hold together longer. That's not my situation though, for the most part.
