Since you mention significance of UI to yourself...
Sony has been critiqued for its UI...it is, after all, a 'consumer electronics' company that offers some still cameras, and it is not a 'photographic equipment' company that designs its products for professional industry users and for amateurs.
"The Sony A7R has terrific hardware features but as with its siblings, Sony falls short in offering total system usability out of the box: no-nonsense non-confusing usability. Instead, complexity and no thought given to the overall experience unless the user deeply engages to essentially reprogram all the buttons to bypass the issues.
"Sometimes dedicated buttons are the answer, and here the A7R falls a little short, relying instead on buttons that o0ften lead to menus rather than simple toggles (several keypresses to get anything done). "
"a6300 menu system
"It’s no secret that Sony’s in-camera menus are disliked by the majority of its users. Sony cameras have a steep learning curve as the menu layout is so convoluted and needlessly complex.
There’s really no way to sugarcoat this; Sony needs to go back to the drawing board and reexamine its menu system across its entire camera lineup.
"That all said, after about a week of using the a6300, I began to feel more comfortable navigating the menu system. If you can can get past the initial shock of using such a ludicrously complex system, then it might very well grow on you."
"Sony’s bloated camera menu
"A common complaint among Sony shooters, that I have to agree with, is that the camera menu is very difficult to navigate. It truly seems like Sony outfitted the a6300 with so many features, and tried to stuff them all into a menu, that it can take weeks for new Sony shooters to get used to using the camera.
"This could be easily solved if Sony allowed users to customize the menu a bit more, so that frequently-used features can be quickly accessed. As it stands, Sony only allows assigning custom functions to the camera’s physical buttons, and there aren’t nearly enough of those."
Don't forget that EVF inherently eats up batteries at a faster rate. Plan on carrying multiple batteries when you are are shooting more than about 250-300 shots in a day.