Reading his Biblical Theology is well worth your time! It's been a long time since I've read a book that consistently made me pause and praise God. If you don't know the original languages (I don't) I find it helpful to have a KJV on hand when reading his works so you can be more certain of what specific word or phrase he is referencing.
I debated between the Redemptive HIstory compilation and Pauline Eschatology which is what I'm reading right now. Mr. Vos' specific work on Biblical theology is: