As Tobias said the A7s and GH4 are photo cameras and the form factor is not ideal for most people, the URSA Mini does look like a great camera on paper however it does require you to buy CFast cards (granted most of us have these but this camera requires specific speeds) which are more expensive than SD card or even SSD drives (Such as with the BMPCC 4K). Plus the additional cost of v-mount batteries. It must also be noting that this is not exactly a small camera which is a minor gripe for myself. There is another camera worth considering which is the JVC GY-LS300. It is a little more expensive initially than the URSA Mini however it may work out cheaper in the long run. I myself am currently contending with the choice of the URSA Mini and the LS300. The URSA and C100 are great options for colour correction work, while the size and practicality of the JVC are very strong selling points. The JVC is more along the lines of a broadcast standard camera best suited for documentary films due to it's codec. The Blackmagic as with all their cameras are not exactly run and gun, however the URSA mini can output RAW and Prores 4444 which are great for heavy colour correction and grading. Conversely the JVC on paper can easily be converted into a colour grading monster with the inclusion of an external recorder as it outputs a 4K signal directly from the sensor. I myself am still considering my options. I think an important note that should be made is with higher end cameras it is often subjective, what works for one person does not work for another and you must also consider your work flow and how you specifically want to you this camera day to day.