Technically "EVIL" stands for Electronic Viewfinder Interchangeable Lens. Not all mirrorless cameras are EVILs, not all EVILs are mirrorless (e.g. Sony SLT Alpha). NX300 doesn't have viewfinder so if you want it you have to buy it separately. Are you sure you want EVIL and not mirrorless?
I suggest go with a more established brand so that is easier to get lenses later. Sony have very good lens lineup nowadays, but one year ago most were still not out or just released. NEX-6 is the most complete NEX for mainstream users, but 3 and 5 have just as good quality, but no viewfinder and less manual controls. Olympus/Panasonic share the lenses, but Olympus ones are not stabilised so better to get Olympus body (EPL-5 is very good as recommended above) then you have flexibility with the lenses - unless you want DSLR-shaped then you must go with Panasonic.
I would stay away from Samsung for now, very unpopular format, no resale value (important if you want to experiment different lenses), though quality is ok.