Not to be completely contrary to everyone else here, but my favorite digital camera for manual focus is the Sony NEX 5N. Other NEX-line cameras, including the A7, will have the same advantages, so it may apply equally well to all.
The NEX series has a number of really excellent features, great sensors, good image quality and reasonably intuitive controls. But one of the best features for people like me, who shot pretty much nothing but manual glass on one, is Focus Peaking.
Focus Peaking electronically highlights the areas that are in sharp focus in the image, using a color such as yellow, white or red to outline those objects.
I find it to be quite accurate, and it also takes into account depth of field, highlighting areas that are sharp with a lot of yellow, areas that are less sharp with a little yellow, and areas that are unsharp with no yellow at all. Stopped down or wide open it'll let you get a feel for what's sharp, what's acceptable, and what's blurry.
Using it on my NEX, I can safely say it allows me to manual focus in any light, without squinting, without futzling with diopters, and without second guessing myself. Getting the right focus on the right object every single time. And happily, it works either on the LCD screen or the EVF equally well.
Coupling this with the fact that my NEX can mount just about any 35mm camera lens ever made and use it without difficulty, and the NEX has become my backup digital camera for both my M and Pentax K systems.
A universal digital camera body that has superb manual focus peaking to take all the guesswork out of manual focusing, available on the 'bay for less than $500? That's exactly what it is. As a bonus, with the EVF removed, it fits in the smallest pocket of my smallest camera bag, barely taking up any more room than 4 rolls of 35mm film.
As an added bonus, telecompressors/Lens Boosters/Lens Turbos are available to give your 35mm glass the 35mm look even on APS digital sensors, while getting you an extra stop of exposure in the bargain!
Having used one now for almost a year, I have to say I'm finding very little not to like about the combination.