I like both for different reasons. As others have said, a lot of preloved is better quality than available now and of course there are lots of cool designs that houses don’t make anymore. (I go back and forth on getting a YSL Mombasa but there’s no question you couldn’t easily get that shape in YSL or a dupe of it now- the thing that’s stopping me is how impractical it is)
However, I’m not immune to the appeal of trends and sometimes you can love an aesthetic today and hate it in six months & ithat’s you, then I don’t advocate buying designer at several thousand a go and taking the loss unless you have stacks of cash.
I think another thing to bear in mind is everyone on this site is highly handbag literate and knows things like this Michael Kors tote is a dupe for the LV neverful, for example, whereas the majority of people wouldn’t make that connection. MK is just a nice shop in the mall.
There are also people out there who prefer the dupe to the original. Like a lot of people on TPF love Coach and Rebecca Minkoff for example and aren’t actually interested in BV or Chanel some of their designs resemble.
so tldr I wouldn’t write off dupes or preloved I think it’s what works for you.
In the spirit of this discussion, did you know TF stole the 'Mombasa' design from a vintage Gucci design? Mombasa was therefore a dupe

Ford got hailed over the coals for it too, from both Gucci and Kering.