Mikal is a better defender, although his defense dropped off after taking on greater offensive responsibility. He averaged 26/5/3 with 1.8 TOs on 61% TS after being traded to the nets. JB has shown more in the playoffs but also is a turnover machine sometimes. He averaged 27/7/4 with 2.9 TOs on 58% TS. Personally, I think for now Brown is the better player, mostly because he’s a better rebounder and iso scorer. I think Mikal can easily overtake him this season if he shows more in his bag.
If you have an established team and need to put one extra piece around it, Mikal. Most of his career as a jack of all trades 3rd/4th option behind superstars.
If you are starting from scratch, JB. Established 2nd option for a very long time, all NBA.