Stave or shield while in group

A lot of people prefer to use a stave while leveling. Some people always hold back from it because of the following logical reason.
Shield is not taken for the Block Value and its Mitigation.
In the case, why, you may wonder, most of user prefer shield then? There are tow main reasons for that: mana sockets and extra stats. Even though the extra Block value is like the icing on a cake the above two reasons are really more worthwhile than anything else. I would not ditch staves though as they have some nice stats that can help out while soloing. Whenever you see a good one, please feel free to test it out.