Its over twenty years since I regularly worked on mainly UK built caravans, and since then all the major brands have made some major changes to the way their caravans are built. I would love to be able to say some of the problems of old have been eradicated, but sadly the reports we see on this forum suggest that whilst details of problems may be different now, the underlying causes are still present.
You will find that some caravan owners can honestly report they have had no problems with their caravans, which is important becasue it proves the the manufacturer can build a fully working caravan, But the problem is they simply can't do it consistently.
What this means is, whilst there are some brands which seem to have certain repeat failure modes, none of the manufacturers can hold their heads up with pride as its more like pot luck as to whether the caravan you buy has been put together correctly.
Unfortunately, even doing your homework and looking at failure rates isn't going to guarantee any caravan you choose will be fault free.
In some respects going for a young secondhand model may well be a good idea, as hopefully most of the major issues should have been put right by the first owner, But it also begs the question, why are they selling it? That's why having an independent inspection carried out can be so important.