Almost exactly what my journey was. When I was a kid, I watched the hell out of TOS, TAS (reruns- I was born in the mid 70's) and, even though I thought it was a major step down in "entertainment value," TNG. I couldn't hold on to DS9, despite my thinking that the pilot episode was brilliant. I tried to come back around "Way of the Warrior," but the serialization killed it for me, as I felt like I had missed too much. VOY didn't last 6-7 episodes and I bounced on that. ENT I barely watched. Since the 2009 timeframe, I've since gone back and watched (and loved) all of DS9 and really liked ENT as well (although not as anything other than casual comfort food). VOY I still can't do. And God knows I've tried.
I'm older, I was in my early teens when I discovered TOS re-runs in the early 70's. Like you, watched the hell out of TOS and TAS during that decade. I bought all of the James Blish and Alan Dean Foster adaptations and anything else I could get my hands on. I remember mowing lawns to save for the full James Blish novel collection from the little book shop in my middle school before school closed for the summer.
Then the movies. I was thrilled to see the crew back in action, each movie better than the last.
When TNG came out, I was a little resistant... who was this new crew? I was worried people would forget about TOS, but it was respectful of the original and Gene's vision, and it eventually won me over. I loved everythig about the show. The updated ship, the computer graphics,and the special effects were great, and the stories were great. I liked that they didn't talk down to the audience, or dumb down the technology the way the network insisted they do on TOS.
I don't know why you didn't like DS9 and VOY.
TNG, DS9 and VOY didn't really hit their stride until they were at least two seasons in. DS9 had quite a few top notch stories and an good serialized plot. Voyager eventually became my favorite Star Trek series. As good as TNG was, it often reminds me of a safe luxury cruise ship in space, but Voyager felt more "raw" like TOS, and Janeway was a more direct captain.
None of the series are perfect including TOS... TOS didn't really develop the middle tier characters very much, and there was so many stupid inconsistencies in the backstory and plots. In Voyager's case I think "B'Elanna" and "Neelix" could have been cast better. Roxanne Dawson played 'B'Elanna' too self-loathing and hateful, and 'Neelix" and Ethan Phillips weren't a particularly good fit, either. But you have to look past the inadequacies of every one of the series...
I honestly can't wrap my head around "I only lasted a few episodes, or barely watched". You are missing out on some really great science fiction stories... maybe because you didn't give yourself time to get to know the characters? We watched every episode of TOS 60 times in re-runs because there was only 3 seasons...it took me a couple of times through before those other crews were as beloved to me as the TOS crew, but the point is it took an investment in time.
I don't care for the "Kelvin" movies. I don't think Gene would have been OK with them, I don't think we needed to re-imagine TOS, and after two decades of great original series and new characters, it seemed cheap to go back to the TOS well instead of coming up with something new and original. When I was a kid, Star Trek fired my imagination; The final frontier might be our greatest adventure. It's not the same when the story takes place in an alternate universe. That was ALWAYS the difference between Star Trek and Star Wars. On second thought, never mind that.
Star Trek is to Star Wars as Braveheart is to Lord of the Rings.
Others may not agree, but whatever.