If you want a mid drive, you want to convert a bike and you want a torque sensor.

Then consider a TSDZ2.

If you want a mid drive, you want to convert a bike and you a fine with a cadence sensor.

Then consider a Bafang (Bbs02b or Bbshd).A few things about the TSDZ2. It is not as powerful, but probably powerful enough. The plastic blue gear that come with the motor is known to wear out if you ride it hard. The brass replacement is noisy.

The open source for the Tsdz2 is very cool, like the ability to use different battery voltage.

I must say I have 2 Bbs02 bikes and I am overall happy with them, but I find the Tsdz2 with the torque sensor very appealing especially with the open source.