I wondered the same thing when I was first starting to think about a 22 Cruiser. So, I did tons of reading and then looked at a number of boats of different vintages. Here are my thoughts:
1) There is no one magic best year, and likewise, no worst one. Sometimes you hear that the older ones are much better built, but I didn't really notice that as a rule. Neither did I notice the newer ones being superior ("newer" for me was around 2008; it's quite possible that the boats built in the most recent few years are better, but they don't really publicize the improvements, so it's hard to know. In any case, I was mostly looking at boats from 1987 to 2008 or so).
2) C-Dorys of any year are reasonably well built, but they are production boats and all have some building/rigging practices of one type or another that are not ideal from my point of view (e.g. unsealed core, silicone bedding, un-tidy wiring, mixed metals riveting rail on, etc.). Again, none of them looked to be in the custom or semi-custom build category. That's typical in production boats in my experience.
3) In any individual used boat, condition is where its at, for me. How was it built, stored, maintained, and used? The latter three may easily eclipse the first one, even if the boat was built perfectly (and none are).
4) For me with the 22's (and because I'm a detail person), it was about figuring out which features came and went when, and then deciding which ones I wanted (that all came together in one boat). Then of course the actual boats available also influenced me. In my case I liked the particular "feature mix" of the early 2000's boats, so that's what I looked for. Others likely prefer other vintages.
So, for me, what I was looking for were as many of these things as I could find in one boat: Early 2000's; stored indoors; grey, red, green, or blue trim; twins; tandem trailer; not too customized or outfitted (I like to choose my own stuff and mount it myself); seller I could work with (would send photos, etc.); purchasable before summer.
In the end, I didn't get twins (but it turns out I prefer the single because I use the big swim platform all the time), and the seller was a pain to work with (but otherwise the boat was just what I wanted, so I dealt with it).
So anyway, upshot is, I didn't see any years that were built terribly - and neither did I see any years that were built perfectly. What I did find was a progression of feature changes that influenced what year range of boat I was looking for. And plus of course condition, condition, condition!
