I bought an Oppo 203 a few years ago so I could buy 4k versions of the films I really loved, rather than buying normal blu ray and then replacing. Pretty happy with it, though older films vary pretty significantly in how they transfer to 4k. In terms of buying straight away or waiting for the price to drop - depends on how much I love the film.
Dolby vision seems like a slightly poor relative to HDR from what I can see, and it seems like HDR adds as much to older films as the enhanced resolution.
I'm disc all the way (with the odd bit of streaming where there's no alternative), but come from an age group where collecting felt important. My (adult) kids have no physical media to speak of, other than eldest's vinyl.