I was on same situation (multi-million company with 60 cameras and couting) thinking to select somethining that could be a standar for all our facilties of our company, I went throught almost 2 month of research, I started writing down pro and cons of mayor software, I use a the information of IPVM, which is great source by the way, I get MY conclusion that for OUR case OnSSi is the best, it has the engine of Milestone but they developed ther own "Client" (interface to see the video), we like the clean inferface, and few and simple menu options that make it easy to use; wide range of 3rd party applicationts, server redundancy, etc. in my opinion it is expensive, but for a multi-million company and are the options it can offer, is a excellent option.
I read some bad reviews, but as you maybe see on amazon, there is always somebody who do not like a product. We get a demo for 30 days, we tested, showed to our people and we like it.
as they say, it all deppend what your need now and what you will have in the future (access control, license plate recognition) etc. the budget, etc.
I hope this help you,