This is not intended by any means to be a comprehensive review of these platforms.
I'm really liking this challenge, because it fits right in with one of my goals, which is to find a way to accomplish what I want to accomplish using as few different platforms as possible. I am currently using 5 different platforms at different depth levels (2 of them are required by my school district; Edmodo is not one of them), and would ideally like to reduce that to 3.
That I will continue to use the school website (through SchoolWorld) to disseminate information to students and parents is a given, so at the very least that will remain a platform that I use. Our district uses schooltool for management of internal data, including grades. This includes a student/parent portal feature which allows ongoing access to information about assignments and grades.
Aside from the platforms used district-wide, I have also embraced wikispaces. I like that students can collaborate with one another via messages, and can edit one another's work. I LOVE that all changes to any page are forwarded to me via email, and a history is available. This was particularly useful when a well-meaning student accidentally deleted the home page for his class, and it was an unbelievably simple fix for me -- I don't even think he ever knew what he had done.
I also love the capability of wikispaces to be used as an eportfolio for digital student work. It supports embedding many different types of work (goanimate, voki, wallwisher -- although due to repeated "glitches" I have switched to linoit for an online blackboard, glogster, slideshare, bitstrips, and screencastomatic, to name the ones I have used). I have had issues with certain cloud apps: empressr and sketchcast, but I have posted links to the student work, so it is still a worthwhile option in my opinion. Image files are also very easily embeddable.
Collaborize Classroom is another platform I have dabbled with. It's format seems to be more or less a directed class blog. What I like about it is the capability to create class polls, and get ongoing data. For example, with a French 3 class working on the future tense, I put forth several specific questions about what life will be like in 25 years (will people be vacationing on the moon? etc.) and students voted whether they thought it was impossible, unlikely, possible, or definite, then we discussed the results in class. For the same poll questions, they had to post longer comments giving reasons why they voted the way they did. However, with blogpolls, I will be able to do the same thing in wikispaces. Also, student feedback on Collaborize Classroom was that many had difficulty logging in, even though I had sent invitations. So, bottom line, I will likely not be using this platform in the future.
Which brings me to Edmodo. It's a great site for teachers whose districts have not made the leap to digital information storage, but for me, it just seems to be redundant. I do like the community aspect, and as I did sign up for an account, I will check that periodically if for no other reason than to continue building my PLN, but beyond that, probably not.