Some would suggest counting the pages on the known problems thread of the various manufacturers as an indicator of quality. If it were only that simple. How many forum members are owners of the various ebikes? How many posts on the threads are issues vs offers of solutions and feedback from the manufacturer? Do yourself a favor and read some of the threads/posts and not just count pages.
Ultimately, you will have to live with your choice. Ask for advice, but also research, test drive, and research some more.
Ultimately, you will have to live with your choice. Ask for advice, but also research, test drive, and research some more.