Who is your Blog Provider? Why that provider?

As one of the student performance objective for Middle States Reaccreditation at my school, St. Benedict's Prep in Newark, NJ, we hope to improve our students' writing skills.  Included as one of our measurements for this goal is an increase in the number of students completing proficient blogs.  

In the documents submitted to Middle States, the SBP Planning Team indicated the belief that increased opportunities for students to write will improve the overall writing skills of SBP students, especially when the writing is moderated by an educator, and when the writing is aimed at a particular audience.  Writing also improves reading skills.  Education research has evidence of such effect of writing, indicated in a recent meta-analysis of a large number of studies on reading and writing in schools (Graham & Herbert, 11).   This belief is the foundation of the implementation of blogs at SBP, which will offer opportunities for students to produce good writing.

I am the main proponent of blog implementation at SBP, and I've been writing (blogging) more about it recently.  My thoughts are here.

Which blog provider does your classroom or school use for student blogs?  Have you tried more than one provider?  What were your experiences?  I appreciate your input.  Thanks.