I would give Grimes the defensive edge, but Hart is a better player (right now).
The combo I dont like is Brunson/RJ. That's when our defense comes apart. You cant hide two guys and we eventually get lit up when they are together too long. I'm GREAT with running this very young squad back next year. If it was up to me I would start Brunson/Grimes/Hart and bring IQ/RJ off the bench where RJ plays his best and you can always finish with whoever but this limits the amount of time RJ/Brunson are together