If you add in reliability, parts availability, battery quality, number of trained service personnel, commitment to 10 years of parts availability and tech support, after the last year of production on a model and the low number of failures and replacements relative to market share, Bosch emerges as a clearly the best all around. Yes the Brose motor is quieter, lighter and has greater torque, but it doesn't come close in these other important factors.
I agree that Brose may not be (at least for now) as reliable as Bosch , Yamaha , Shimano. Bosch have good warranty processing and reliability record. They also have a good number of trained personnel.
That being said, 10 year parts commitment is marketing.
Most people will not keep an ebike for 10 years, and even if they do,
1. One should mention that Bosch LOCKS the system so even after the warranty period you can not use 3rd party batteries/ components and have to buy parts from Bosch. Needless to say their oem parts are very expensive, $55 for an intuvia controller which is nothing more than 4 buttons (you can buy a keyboard with more than 100 keys for less than $9). Intuvia display which is an extremely simple unit with an lcd screen from 90's is $135, you can get an entry level smart phones(which are on a different level when it comes to functionality) today for half that price. Not to mention the price of $900 for a 500wh battery.
2. Sometimes you may need something that is better than the oem parts. For example I am willing to pay more for a 800wh capacity battery. Since the frame is not designed for dual battery, the only option is buy and carry a second battery which is inconvenient. Likewise if the system was not locked then a third party, even an undergrad student can write a nice little app for smartphones that can be more functional than Cobi or Nyon.
So, Bosch is more likely to make good money on a customer rather than doing her a favor if she wants to keep a bike for 10 years.
3. Even under warranty if you need something as simple as a firmware update and need it done by a shop which you have not purchased the bike from then you need to pay. This is not the lbs's fault since they actually PAY bosch to get the training and not compensated when they do these updates(This was the case in 2019, I don't know if they have changed their ways).
I will not have any of these problems with a Brose system because it is not locked and Shimano let's third party batteries to be used with their system at least.
So I don't know if I can say they are the best around. They are good but have their own issues.
On a side note: Having a closed, locked system has its advantages , diagnosis is somewhat easier, if something goes wrong parts are just replaced and designing becomes easier since you can treat the motor/battery as any other component on the bike. But most of the time these benefit the bike manufacturer not the customer.
