I've been going through somewhat the same process of trying to find a monitoring company, and I think you will find that a lot depends on what you are monitoring (Elk, Omni, DSC, Honeywell, etc), how you want it monitored (POTS, internet, cellular, dual path), what extra equipment, if any, will be needed to do that (Uplink, Telguard, ipDatatel), and your price sensitivity.
There are tons of threads on here in addition to the 4 RAL cited above, with lots of good information, but some of the older ones do not reflect what is now available or technology changes.
Once you define what you think you want, call two or three of the companies that look like a good fit for you and see if they can do it as you would like it done.