All of these vendor solutions limit customization and personalization. You may want to have a single portal. These can't do that. Some of these solutions have advertising on them that you do not control. Customization will probably be different for your different roles, or a portal might give you a view based on all your roles.
Some roles demand very specific customization.
The registrar , e.g., subscribes to the student info channel, but has access to all students and has global update privileges. A student subscribes to the same channel but can only see her own info and has no update privileges. Customization includes what initial channels you subscribe to, what privileges you have to read, search and update items, what channels you can add, what personalization you can do, etc. Both customization and personalization must be saved for each of your roles. These may be saved with the same or different technologies.