My journey went something like this:
The first album I ever bought was The Game by Queen. I don't recall exactly when I bought it, but I know Another One Bites the Dust started blowing up the charts in late 1980, so I am guessing I picked it up in the first half of 1981 or so. I began gravitating to other stuff on the radio like Journey (Escape album), Men At Work, Hall & Oates, and things like that. In fact, I'm pretty sure the next album I bought was from Hall & Oates, and the third was Men At Work. But then in early 1983, some hard rock band with a goofy name from England release an album that blew my mind. And with the release of Pyromania, Def Leppard became my first "official" favorite band.
Through my high school years, I began to gravitate to other similar hard rock bands like Scorpions, Y&T, Whitesnake, Bon Jovi, Van Halen, and the like. But I also had a group of friends that were heavily into the new wave scene and bands like Depeche Mode (before Music for the Masses), Siouxsie & the Banshees, Madness, and New Order. It took my awhile to get into truly heavy music of that time. But I liked the guitar-driven, heavy-ish sound of those hard rock bands the best. But the melody and some of the cool keyboard work of the new wave artist also struck a chord (pun intended), and I would often lament that there wasn't a band that successfully blended the heaviness with keyboards without sounding cheesy. I imagined that there must be some way to get the best of both words and create a really huge, diverse sound. This would become important for where my tastes would go later on.
Although my tastes expanded, Def Leppard remained my favorite for a long time, and my go-to remained similar types of music. In 1989, a guy I knew kept insisting that I listen to Operation: Mindcrime. I did. And at first, I didn't get it. But it eventually clicked, largely as a result of hearing a pretty solid cover of I Don't Believe In Love by a covers band at the locally-infamous known as the Thunderbird Bar & Grill in Jacksonville, NC (mentioning it by name makes me feel like I need a shower). It took me a little while, but I came to love the album. But it wasn't until Empire that my mind was truly opened to this band, and then replaced Def Leppard as my new favorite. This also was a time when my musical horizons began to expand, and I began exploring and embracing heavier and more complex music.
In 1992, I heard DT on the radio, liked them, and bought Images & Words. Liked it. This was FINALLY the band that managed to marry heavy guitars, soaring vocals, and complex but huge, atmospheric keyboards in a way that sounded really good. But there was still a lot I didn't "get." Still a solid album though, and I would revisit it regularly through the years, despite never pulling the trigger on Awake, A Change of Seasons, or Falling Into Infinity. That would change in 1999 when I saw SFAM on the shelf at Tower Records in Woodland Hills, California. Bought it. Loved it. Could this be my new favorite band? Could they possibly dethrone Queensryche from the lofty perch they had held in my heart since 1990? I wasn't sure at first. But then Queensryche released Q2K, so...
DT has remained my favorite ever since. And their influence has led me to explore more progressive metal and progressive rock, some power metal, and some symphonic metal. I can't say I am a true fan of any of those genres a whole. They tend to be very hit-and-miss for me. There are a lot of misses. But when bands hit, they can often tend to be right up my alley and be just what I like when it comes to marrying heavy guitars with layers of melody and complexity.
So in summary, my favorite bands list looks something like:
1983-1990: Def Leppard
1990-1999 or 2000: Queensryche
1999 or 2000-present: Dream Theater
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Footnote/epilogue/random-related-thoughts:
I still hold Def Leppard's 3 album run of HnD-Pyromania-Hysteria in VERY high regard, despite kind of moving on from that sub-genre. I liked Retro-Active from start to finish, which makes sense given that the bulk of it came from that same era. And I felt like Euphoria was a terrific return to form. But despite some songs here and there that I enjoy from the rest of their catalog, the rest of it is a bit of a let-down for me.
For Queensyryche, I love the original lineup albums through HITNF to this day. I also truly love the two TLT-era albums. Q2K through D2C are very hit-and-miss for me, as discussed in a couple of threads. There is some stuff I like a lot, some stuff that is incredibly sub-par, and some in the middle.
In the late '80s and early '90s, I came late to the game with thrash, which got me moving in a heavier direction. But I was a bit selective. I really like Metallica from RTL through the Black Album, and don't really care about the rest of their catalog. Megadeth could do no wrong from Rust through Youthanasia. I have still purchased everything since, and "like" a lot, but don't love it. A few other bands like Testament and Flotsam & Jetsam are case-by-case bands for me where I may like a few albums or songs here and there, but don't feel compelled to buy many albums.
I also grew up in the '80s with an irrational bias against '60s and '70s rock, and that has been hard to shake. I have warmed up to a lot of it, but there is still a definite wall that keeps me from liking some of it. Some is the production from that era. Some is the general sound. I still don't like and can't get into a lot of it. Bands like Zep, Aerosmith, and a lot of Rush even just grates on me. I can appreciate the talent of those bands, but I just don't like them.