It is hard to recommend any Blu-ray 4k player apart from the Oppo or the Cambridge at the moment due to all the confusion and lack of support on decks regarding Dolby Vision support. I think I would stick with the Oppo as it has DACs. Neither are cheap.
The 2017 Lg oleds have dynamic tone mapping that seems to negate the need for dolby vision (you have a fast enough processor to evaluate the brightness frame by frame), and equally according to Vincents's comments it/DV is of less benefit than hdr on a higher nit lcd display (see qled thread) so choosing a player with dv may not be essential.
I understand LG player has DV too, anyway.
The oppo dacs, like the ub900 are just for 2.0 output, if you do not have a a/v processor too - afaik,
the lesser ub700 (similar build quality in tear-downs), with same colour processor, is the 900 without dacs and can be had for <£200, which is less than 1/3 of OPPO, so the oppo seems a big premium.
Have they now fixed the oppo's infancy problems (tone mapping ?) that had given negative comments versus the ub900 too ?