If I was a consultant, I would recommend an independent VMS because this would provide my customer with choices, choices between different IP camera manufacturers and their products.(Stay with me - I'll get back to cameras in a second)
For example, these camera manufacturers market their products, my customer goes out/hears about this great new camera and decides they want the benefits of such and such a product. They call me up, but I sold them this Hikvision NVR. Well that camera that really adds value to the customer's surveillance solution, guess what it isn't compatible.
So turn this around, we sell Hikvision cameras - what VMS would you recommend? A Hikvision NVR is really the only thing I could recommend.
As a systems integrator, we know that it is the integration between the VMS and the camera that matters/is important.
Can we change frame rate on motion, can we change resolution of the camera when a door is propped open? Can the customer or technician push changes to the cameras through the VMS directly or do they have to go to the web page of the camera directly or use the camera manufactures tool to do so? Take a new panoramic camera from Hikvision, who cares about it if it isn't supported by anyone, who cares that it is $250, dewarping is only possible with a Hikvision NVR I am assuming. Oh yeah they come out with a new one every three months.
The answer use to be Axis - they had tremendous relationships with the various major VMS companies. This is no longer true. Samsung/Hanwha paid to play - a lot of money was spent to get into the major VMSs and it worked, they come out with a new camera (and they have - too many IMO) and in general the next release of the VMS supports those features.
Look out for Vivotek - they have done and are doing the same thing.
In contrast take EXACQ - they don't integrate with any camera in general - they just get the video to work. That is not integration. One camera supports motion on the edge, the next camera in the series - it doesn't. I would be scared to be a consultant in these situations, you specify a camera - are you sure what is possible with that camera and the VMS - well you better check if its Hikvsion, who knows.