Buying a 4k TV this weekend, want some opinions on these models

Hello,

Making my first foray into 4k. Have space for either a 65" or 70" TV. Could I get some thoughts on the following TVs?

65" TVs:

Sony XBR-65X750D 65" $1,199

Samsung UN65MU630DFXZA 65" $1,149

Vizio E65-E1 65" $899

70" TVs:

Vizio E70-E3 70" $1,199

Vizio E70U-D3 70" $1,329