Live on post or off post ?

my huband is going active duity army! we have 3 kids and are excited to be a military family! we were woundering if it would be better for us to live on or off post? as of right now my husband is going in as a E4 62B switching from national guard to active ARMY!!! which is cheaper and which would be the best bet for our kids school wise and safty wise too? thank you and GOD BLESS