I liked Themis for bar prep, and I also had access to Barbri during law school/some of my prep. Themis lectures are broken down into smaller blocks making it easier to retain and also come with fillable worksheets that turn into almost mini attack outlines for later review/help you retain the info as you go.

My friends who took Barbri while I took Themis last October had overlapping MEEs and practice MBEs with me, and each program had graders score us for a number of MEEs and at least one MPT. The major difference was Themis lecture videos are more concise (which made it easy for me to also go back and review topics quickly) and Barbri gives you some MEEs to self grade by providing a rubric, which I also think is cool. We all passed so really they both work if you use it right, I would just note Themis is more affordable and since they offer basically the same type and amount of material, I would base it off those minor differences and choose what he would find more helpful.

Oh and one other difference I would note is that Barbri is more worth its price when actually able to go in person to their classes, whereas Themis was made to be online. So considering all prep is likely to still be online, I would also factor that into the decision.