OK, first, a caveat: I don't own and have not owned SecuritySpy. Mainly because it's VERY expensive for what it does with the number of cameras I have/want. I used EvoCam for a while, but it's at end of life and it was a processor hog.
That said, for anyone willing to fiddle a bit, and already owning a Mac less than 5 years old, it's just plainly a no-brainer: Indigo + Security Camera Plugin from Bertbeats Security Spy hands down.
Why?
With any reasonable number of cameras, SecuritySpy costs MORE than Indigo. And does MUCH LESS. With Indigo + SC plugin, you get a theoretically infinite number of cameras, with motion detection, recording, etc. for a price lower than SecuritySpy charges for 8 cameras. And of course, SS does not control/monitor a dozen other protocols and literally thousands of other kinds of home automation devices from pool heaters to door sensors to WIFI access points, from 20 year old X10 plugs to brand-new on the market Fibaro key fob controllers, from standard Foscam HD cameras to software based IP cams running on old cell phones.
Yes, there's a Security Spy plugin for Indigo that I hear is excellent. But for new users who don't already own SS, I can't imagine why they would buy it if they've already decided on Indigo! And if someone is a Mac user who doesn't mind installing things like brew, imagemagick and pillow and is thinking about SecuritySpy, they would be well served to pick Indigo even if all they want to do is monitor cameras.