My ranking hasn't changed but there are some things to note. I'll get to that in a minute.
1. TOS -- Is my favorite because it's the one that interested me the most.
2. DS9 -- Followed this one through to the end. I couldn't wait to see what would happen next. Like all stories that have a beginning, middle, and end, when it was over, it was over. My interested in TOS was more open-ended.
3. TNG -- I watched this show every day in the early-to-mid-'90s but I don't feel much attachment to the series. With TNG, it depends on the episode more than TOS and DS9.
4. VOY -- The concept of this series interested me more than any of the others. In 1995, I wanted this one to be my favorite but its erratic episode quality was frustrating. After 1999 and Ron Moore's falling out with Brannon Braga, I gave up. I didn't see the rest of the series until 2008.
5. ENT -- Never really watched this one. Don't feel much of a desire to. And, at the time, Ron Moore's falling out was still fresh in my mind. I saw five of the first six episodes and it didn't grab me. I saw a handful fourth season episodes and they were okay, but they didn't hook me into the series either. "Demons" and "Terra Prime" were very good though. More of this and I would've been interested... but, as we know, it wasn't meant to be.
Now for the notation. I'm burned out on TOS, I'm burned out on DS9, and I've still had my fill of TNG. I've also watched various episodes of these series for Old Time's Sake over the years. Not only am I burned out, I'm even tired of watching my favorites. It's enough.
VOY is the series I'm most likely to watch these days because, with the exception of "Endgame", I didn't watch the series at all
from 1999 to 2007, when I caught a few episodes on Spike, then I took a plunge and watched the whole series in 2008. Most of the episodes I'd either only seen once, over a decade earlier, or not at all. So it was kind of like watching a new series. Sometimes, I forgot what happened because of how much time had passed, so I didn't always know what was going to happen next. Since I'm not burned out on VOY, and had a long break away from it, it's the series I'm most likely to watch these days instead of TOS, TNG, or DS9.