For Education Portal-Which is the Best Script ?

I have planned to start up an Educational Portal. I dont what other portals do, but I need:
1. Paid Subscription to Study Materials
2. Well Organized Online Test Taking System

I dont want to combine 2/3 Scripts for this and baffle myself. A single package which has atleast these two requirements would suffice me.

I have heard about 3 CMS which are working best for Educational Portals.
1. Moodle
2. DrupalEd
3. Joomla

I dont have any idea on these three CMS. I am somewhat strong in Wordpress and I am using that in more than 40 sites. I am not sure what CMS to install for this Portal.

Any Experiences, comments, Suggestions for these 3 ?
Is there anything which I could try for better results (other than these 3) ?

 

The only one designed for educational use that I've heard of is moodle, but I don't know much about it. I'm also in the educational field so I do know that many school districts use it, but beyond that, I'm not much help!

 

Could you share the experience of using Moodle ?
Does it have "ONline Test taking" and Email Subscriptions, Notifications for members ?
And Paid Subscriptions for Study Materials ?

 

I've never used it myself, but I am aware of school districts that have it employed.

 

Can you give their url's please,
I would go and register in their site, and make sure that my requirements are satisfied in moodle !
Thanks for your view, Any other views ?