I have never ridden or even seen one. But since Bulls was formed by a cooperative of bicycle dealers, it does not surprise me that they would know how to design good bikes. That said, I know there are other good bikes too. The question should really be, what is the best e-bike for you?
When researching for my recent ebike purchase, I was putting Bulls in the same category as Stromers: European-made, very high-quality, and expensive. If it was in my price range, I would definitely have seriously considered.
Using the word "best" opens up a whole debate. It really boils down to personal preference and fit of the bike, and riding style. My original intention was to buy a Bulls bike, but a demo deal on a Haibike made the decision much easier for me.