I like Sony. I've got two and, depending on your needs, I'd go for the cheapest one that does what I need. Personally, I don't see a need for me to hunt down a region free player since I've never had a disc my units can't play. Nor will I search out discs from another region. I'll just buy locally.
Given the cost of these things, I see them as a commodity. I don't see myself jumping on the 4k bandwagon until the manufacturers settle on a common spec and they start manufacturing to that. By that time, I'll then have a 4k TV and a new receiver to pass everything through and extract the sound.
And, I'll wait until a goodly number of 4k discs becomes available before jumping on anyway.