cen@jkt
1918
For me, it's easy decision:
the EVF. I like shooting with an EVF, what you see is what you get. No guessing around, no need for review. More accurate at wider apperture and with wide angle lenses. And I can use any lens on A7 with adaptors. And I don't like changing lenses on the go, hence 2 identical bodies would be prefferable. And I can get (almost) A7 and A7s with 1 Leica body.
It's different shooting style, not better or worse. I borrowed my friend's A7s to Tibet and like it a lot due to its high ISO capability. No tripod needed. Holding the A7s for a long time is also more comfortable than holding an M9.
I bought the A7 because it's cheap at the moment and I needed something to put my Leica lenses on

. Full frame for $1k! That's a very reasonable admission price for you to try using it, don't you think so? Try it for a month, and sell it if you don't like it. Or upgrade to A7s and A7ii.
If you like shooting with a rangefinder, then the new M is the only solution. But I don't want to spend that amount money on a camera body anymore. And I still have the ultimate rangefinder, RD1 for fun
cen@jkt