Both are ok but proprietary and need frames to fit them. The Bafang BBS02 that is adaptable to almost all bike frames including fat bikes, legal 750w, can be run either PAS (although not as sophisticated), throttle or both with a non proprietary type battery will do everything either Bosch, Yamaha, Brose or any of the other mid drives being sold by the big manufacturers will at a much lower price. They have proven to be quite reliable if run at their recommended voltage also.
And NZPeter you are right that Yamaha made mid drives long ago. I had a Trek with one over 10 years ago. Panasonic had a similar drive but those systems, although robust, were limited by the battery technology of that time which matched with the 250w power restrictions of the EU made for a less than inspiring and short range ride. They did wet the appetite for what is on the plate these days however.
