gh4students

For what it's worth, my students and I tested the a7s, GH4, 5D MKIII (h264, not Raw), NX1, A6000, 70D, and BMPCC for low light noise + color performance, and all three projects chose to shoot with the a7s. Two of them are low-light night shoots, but one is day. For low light, obviously the a7s wins by a long way over the others -- in noise and color. (Once you start digging into the picture profile menus, you can really carve into the color.) 5D was closest, of course. The rest were just painful in low light (when compared with a7s). We even tried a Voigtlander .95 wide open on the GH4 to see how it would compare to the a7s with a Jupiter 9 at 2.8, and it wasn't close (for noise); the a7s/jupiter won by a mile.
In daylight, they were all nice in their own ways. Dynamic range of a7s and BMPCC is nice, all things being equal, but when money is tight, I'd personally take the cheaper camera and spend the extra on lenses and kit. I think they're all capable of good color. Different looks, and different paths to get there, but I've gotten images I like out of all of them. 
In good light, NX1 and 5D probably take the least effort to get good color, but that h265 on the NX1 isn't a lot of fun right now. It is less work than 5D Raw, but still a big pain compared to other cameras, IMO. Personally, if I was going to go through the pain of converting every shot, I'd probably choose 5D ML Raw right now. I think that gives the best color of the lot, but you gotta really want it.
That said, the whole thing is so personal. What works for you -- the camera, ecosystem, and workflow that you will enjoy -- is so different from anyone else. I tried shooting the NX1 for a week and sent it back, preferring to keep my GH4 and a6000. It's a nice camera, but it didn't really speak to me. I felt like I kept having to talk myself into loving it, and then I realized that I just didn't love it.
I tried the a7s for a week, and now I'm going to sell my GH4 and a6000. I am truly loving this camera, for both stills and video. It's brought a joy back to the art and craft of image for me. Are there better cameras out there? I don't know, and I don't care any more because I'm loving what I can do with it.
So I say, if the a7s isn't bringing you that joy of shooting, sell it and find the camera that does. Regardless of specs and features: if you love shooting with a camera, you'll shoot with it and find ways to make it work. It doesn't sound like the a7s is that camera for you.

For what it's worth, my students and I tested the a7s, GH4, 5D MKIII (h264, not Raw), NX1, A6000, 70D, and BMPCC for low light noise + color performance, and all three projects chose to shoot with the a7s. Two of them are low-light night shoots, but one is day. For low light, obviously the a7s wins by a long way over the others -- in noise and color. (Once you start digging into the picture profile menus, you can really carve into the color.) 5D was closest, of course. The rest were just painful in low light (when compared with a7s). We even tried a Voigtlander .95 wide open on the GH4 to see how it would compare to the a7s with a Jupiter 9 at 2.8, and it wasn't close (for noise); the a7s/jupiter won by a mile.
In daylight, they were all nice in their own ways. Dynamic range of a7s and BMPCC is nice, all things being equal, but when money is tight, I'd personally take the cheaper camera and spend the extra on lenses and kit. I think they're all capable of good color. Different looks, and different paths to get there, but I've gotten images I like out of all of them. 
In good light, NX1 and 5D probably take the least effort to get good color, but that h265 on the NX1 isn't a lot of fun right now. It is less work than 5D Raw, but still a big pain compared to other cameras, IMO. Personally, if I was going to go through the pain of converting every shot, I'd probably choose 5D ML Raw right now. I think that gives the best color of the lot, but you gotta really want it.
That said, the whole thing is so personal. What works for you -- the camera, ecosystem, and workflow that you will enjoy -- is so different from anyone else. I tried shooting the NX1 for a week and sent it back, preferring to keep my GH4 and a6000. It's a nice camera, but it didn't really speak to me. I felt like I kept having to talk myself into loving it, and then I realized that I just didn't love it.
I tried the a7s for a week, and now I'm going to sell my GH4 and a6000. I am truly loving this camera, for both stills and video. It's brought a joy back to the art and craft of image for me. Are there better cameras out there? I don't know, and I don't care any more because I'm loving what I can do with it.
So I say, if the a7s isn't bringing you that joy of shooting, sell it and find the camera that does. Regardless of specs and features: if you love shooting with a camera, you'll shoot with it and find ways to make it work. It doesn't sound like the a7s is that camera for you.

For what it's worth, my students and I tested the a7s, GH4, 5D MKIII (h264, not Raw), NX1, A6000, 70D, and BMPCC for low light noise + color performance, and all three projects chose to shoot with the a7s. Two of them are low-light night shoots, but one is day. For low light, obviously the a7s wins by a long way over the others -- in noise and color. (Once you start digging into the picture profile menus, you can really carve into the color.) 5D was closest, of course. The rest were just painful in low light (when compared with a7s). We even tried a Voigtlander .95 wide open on the GH4 to see how it would compare to the a7s with a Jupiter 9 at 2.8, and it wasn't close (for noise); the a7s/jupiter won by a mile.
In daylight, they were all nice in their own ways. Dynamic range of a7s and BMPCC is nice, all things being equal, but when money is tight, I'd personally take the cheaper camera and spend the extra on lenses and kit. I think they're all capable of good color. Different looks, and different paths to get there, but I've gotten images I like out of all of them. 
In good light, NX1 and 5D probably take the least effort to get good color, but that h265 on the NX1 isn't a lot of fun right now. It is less work than 5D Raw, but still a big pain compared to other cameras, IMO. Personally, if I was going to go through the pain of converting every shot, I'd probably choose 5D ML Raw right now. I think that gives the best color of the lot, but you gotta really want it.
That said, the whole thing is so personal. What works for you -- the camera, ecosystem, and workflow that you will enjoy -- is so different from anyone else. I tried shooting the NX1 for a week and sent it back, preferring to keep my GH4 and a6000. It's a nice camera, but it didn't really speak to me. I felt like I kept having to talk myself into loving it, and then I realized that I just didn't love it.
I tried the a7s for a week, and now I'm going to sell my GH4 and a6000. I am truly loving this camera, for both stills and video. It's brought a joy back to the art and craft of image for me. Are there better cameras out there? I don't know, and I don't care any more because I'm loving what I can do with it.
So I say, if the a7s isn't bringing you that joy of shooting, sell it and find the camera that does. Regardless of specs and features: if you love shooting with a camera, you'll shoot with it and find ways to make it work. It doesn't sound like the a7s is that camera for you.