Having said that, while I can call that early 90s stuff my favorite still, I have never had a lull in finding new music I love in adulthood.
In my mid/late 20s I discovered Opeth, Blue October, Muse.
In my 30s I discovered Ghost, Vola, Devin Townsend, Awolnation
Then in my 40s I discover a few albums I couldn't take off repeat, and are by bands I had never heard of - Absolute Elsewhere by Blood Incantation, True North by Borknagar, Take me back to Eden by Sleep Token and The Fundamental Slime... by Nekrogoblikon.
Meanwhile bands that came around in my 30s are still putting out great music like AWOL, Vola, and Ghost
Now, I guess it helps to be a metalhead, because while maybe radio/pop is stale, metal continues to evolve and by most accounts is getting bigger every decade. To me, if you've never gotten into metal then you're just missing out. There is so much great music in that world, and so much of it is not even metal, but it will always be labeled metal and will never be in mainstream media.
Sleep Token is one that finally kinda of broke through. The amount of people arguing whether or not they are metal is mind boggling.. at the end of the day, if a band has had one song in their past that is metal, then by nearly all accounts, they will be labeled metal and treated as metal. Yet they can have have 3/4 of an album be piano and beautiful melodies and texture.. but no one outside of the metal world will know.
Similar to Damnation by Opeth.