I'm not overly familiar with MacArthur's works. Only what I briefly read on Wikipedia. As far as personal use, I use a multitude of resources for preparing sermons, lesson, or any number of teaching material. I've used several commentaries such as Matthew Henry, Gill, Poole, Schofield, Geneva Study Bible, Spurgeon, in addition to scriptures for single paragraphs. And other times, used a single commentary for a whole look at certain topics. The most important element though, is the Word itself. No devotional, or any extensive amount of work should be outside or founded on anything other than the Word itself. Given enough time on topics, one can easily identify and plan sermons with just the Bible, the Scriptures themselves, as it is very thorough and self-explanatory. A Bible dictionary is more than helpful, as are Concordances helping to identify other uses of the same words within scriptures. Some words require more extensive research, as some place names and practices are easily overlooked due to lack of understanding. It is vital to understand every word. As some words are left in Hebrew or Greek or Aramaic, this becomes more difficult. A wise man always does his own homework. Too many preachers use other preacher's work as basis for their sermons. They take the easy way out. So while it may take longer, it is more fruitful in the long run and thorough to do the digging, take the notes, and come to your own conclusions. Then compare those with other's findings. Many people are misled because they never do their own work.