Hello my parents are looking at getting a new tv they have narrowed it down to either the sony kdl55w829bbu or the LG 55UB820V im wondering if anyone has any opinions I know the sony is a good set but is it worth spending the £100 more to get 4k?
Thanks

do your parents care about 4k?

Not really they obviously want best picture quaility they can get but im thinking of future proofing. Also does anyone have opinions on the difference between the two's smart TV OS's

Just be aware that having more pixels on a screen does not mean that the picture will always be better, particularly at roughly the same price point.
A 4K set at a similar price to a Full HD is likely to have a lower quality screen, meaning the contrast, colours, motion handling, viewing angle etc will be worse. This however can be a subjective opinion & the only way to ensure they have the TV they like the picture of is to get them in to a shop, see them working, then support the shop you went to buying from them!