If you intend to override the range of your battery and pedal your way home, the best design is the geared hub motor. These have an internal clutch and do not drag when pedaled. I envision an 80 miles trip next week, but don't want to buy another $630 battery that might get used twice a year and die from lack of charge cycles. Also spare batteries can't be carried into concerts, and are a thief magnet on a bike cabled up in the parking lot.
front hub motors balance the bike better if you carry a lot of cargo, but it takes a special frame to handle the torque. I hung the 18 lb battery from the handlebars and did not find the high weight center a problem.
Mid motors wear out chains, especially if the number of sprockets is over 7. I've owned 2 bike chain tools that didn't work, and find this frustrating since I spliced industrial chain at work, including the "bicycle" 1/8" sprocket size , successfully.
Midmotors delete the choice of several front sprockets, which means one won't be able to pedal up steep hills after the battery is dead.
It does take longer to remove a rear hub motor to change the tube, but I've found tires that cut my number of flats to less than one a year, so I'm willing to take the risk. a selection of wheels seems to mainly be about lightness from today's suppliers, which is not critical on an electric drive bike. Hub motors do come with bad plastic wheels or dual lining aluminum wheels both of which require long stem tubes available only out of state. However I have a collection of steel wheels from the sixties that should be strong enough with a single thickness and normal tubes. You can't buy these anywhere, however
Mid-motor come from major supplier and have a good quality reputation. Reputable brand hub motors seem to mostly come from out of the USA which means your debit card number lives on a server out of the jurisdiction of the FBI. I found one brand geared hub motor with a reputation at a US supplier, but he refused to sell to me because with cargo myself plus bike plus carge weighs an exorbitant 320 lb. Also I owned a 48 v battery which he found to cause a reliability problem. I tried to buy the swiss made geared hub motor but could find no vendor.