I work creating content for VLE's and personally find frog is the best. It may cost money to buy, but it will be supported properly. Moodle is what I us to test on, but I find allot of problems, as it is open source and free, you are basically on your own if it goes wrong. It is buggy and I have problems with files not opening properly. You are more likely to need a tech person to set it all up and support you, which can end up costing allot.
So it is down to if you are want to pay money up front, or having a technical person in school to fix it up.
