I would echo much of what has already been said, especially by Tigger_MK4. The main issue though is that you are merely giving your brief thoughts upon each of the three main titles available, and that you fail either to elaborate upon or illustrate said thoughts. Certainly,you fail to identity, for example, what are the main strengths of Call of Cthulhu -- its mechanics for handling sanity and mental deterioration, the simplicity of its rules, and of course, the aforementioned wealth of support in terms of background and scenarios. Each of the three titles has its strengths and weaknesses, and if you are to compare and contrast them, then doing so requires much more time and attention.
Further, from what you have written it would suggest that you are only looking at each title from a contemporary standpoint as there is no context for any of the three titles you write about. I appreciate that this might call for more knowledge, but it is easy to pick with some reading.
Oh, and you should add Cthulhu Dark, The Laundry, and Achtung! Cthulhu to the list of RPGs influenced and inspired by the works of H.P. Lovecraft.