I mostly follow Dragon Quest out of interest in its greater place in the genre at this point. After playing through DQ8 a few years back, I decided the series is not for me at this point.
I do have a long history with Dragon Quest, with the original game being my first JRPG back in 1989. I played DQ2 a few years later and didn't care much for it (the Cave to Rhone has a well-deserved reputation). I didn't touch the series again until much later with the PSX version of DQ7, which I still regret putting 110 hours into. I suppose I can thank that game for breaking me of the habit of having to finishing long games I stop liking halfway through.
I still ended up going back and playing through the DS versions of DQ4 through DQ6, and the mobile version of DQ3 more recently. Dragon Quest has had a knack for getting me into dungeon-crawling flow states with the explore-battle-victory-explore rhythm, and it generally wasn't tough for me to get started and rolling in the games. Unfortunately, they burn me out quick: almost all of them ended up overstaying their welcome by about ten hours or so. I almost didn't finish DQ4 because of how difficult the boss was.
I do have very nice things to say about DQ5, though. The story in that one still feels well above Horii's other works in the series (at least the ones I've played), and the time progression is something I'd like to see more of in the genre. That one--and the original, years back--are the ones in the series I wanted more of when the credits rolled.