OK, maybe not any help for the particular examples
you've found so far, but I would note that the construction/engineering for the three you name would break down as C&C - first, Catalina - second, and a distant third - Hunter.
Nothing wrong with any of them
-- just know what you are putting your future time and money into.
Condition is the really big thing as the boats age... but still... like houses on dirt, you first need to be aware of differences in footings and foundations and framing
before considering how much $$ to put into restoring windows, shingles and roofing.
Basic construction is important, and "thin"-engineered boats that were were cheaply equipped when new are going to age lots worse after 20 years of exposure to usage and the elements than a stronger boat like a C&C, Tantan, Sabre, CS Yacht, Niagara, or Ericson, to name only a few of the leaders in the aging-with-grace contest.
As you noticed, however, when you find any make of boat that was "rode hard and put away wet" for a long time you need to be skeptical, and cautious.
"Cite an example" whispers someone from the galleries...
OK. Two mid-1980's thirty footers: one a Hunter, the other an Ericson. I have worked on both boats. Stock bilge pumping system in the H was a small Rule centrif. pump with manual switch on a small distribution panel.
Stock bilge pumping system in the Ericson was/is a ParJabsco chamber pump with float switch and
a metal Whale Gusher manual pump adjacent to the helm. Total retail cost of the pump system on the E boat was about $500. compared to about $20. on the H. The rest of each boat, spec wise, is similar. Hull layup and general construction differences are easily apparent, too.
On the used market, one costs twice the other, and is fully offshore-capable. It is all about choices and options... and knowing how much safety you want to buy and where you intend to sail. On 12 knot days in protected waters, they're all good.
boats have their designed-in performance envelope and best-use, and all are valid choices within those parameters... just be aware having masts, hulls, and keels does not make them in any way equal
Nothing here you did not probably already know, either.
ps: for much single handing, try to find a boat with an aft traveler or a bridge deck traveler. I single hand a lot and that was an important factor when looking for a boat. In your price and size range, look for an Ericson or Tantan 33 to compare with your other choices.