The Brose motor is definitely the most quiet ebike motor that I’ve used. The 28mph model is no different. I also find it to be pretty solid in terms of power. Generally speaking, Bosch motors are considered the most powerful, but with the Brose I actually think you get a lot of power with a more “real” feeling cycling experience. They also give you a 675 watt hour battery pack, which is still unrivaled in terms of a single battery system.
We found the Groove motor a little laggy in engagement, with often almost a full rotation of the cranks before the assist engaged - compared with the Gazelle and Vanmoof, the pick-up was frustrating. Putting our issues with the assist to one side, we couldn’t fault the aesthetic: we loves the semi-mixte frame style, a practical non-gender specific design.
The first regularly produced device resembling the modern bicycle was unveiled in 1818. It was called the Dandy Horse. The two-wheeled ride-on Dandy Horse was the brainchild of German inventor Baron Karl Drais, and it featured a handle bar, a padded seat, and two inline wheels of nearly equal size. What it did not feature were pedals; this was a "running machine," thus its name in German, Laufmachine. The Dandy Horse saw only a flicker of popularity, and was largely an historical footnote within a handful of years, though its design is nearly mimicked in the child's balance bike of today.
Kalkhoff's electric-assist bicycles start with the same high-quality, sleekly designed bikes that Kalkhoff has been developing for 90 years. A state-of-the-art, brushless, centrally-located motor provides a smooth, predictable power-assist directly to the drive train. Kalkhoff e-bikes come fully-equipped with a variety of features to ensure that your commute, shopping trip, or outing is safe, comfortable and fun.
It really is a simple e-bike, and while I could go on about the frame (aluminium), and the weight (very light), the experience of using this bike for a few days is more interesting. While it feels like a less high-tech product than others in this list (no gears; a shorter battery life of 30 miles; two modes not three), it basically retails at half the price as those competitors – and I certainly didn't find it to be half as good.
There are individuals who claim to have lost considerable amounts of weight by using an electric bike. A recent prospective cohort study however found that people using e-bikes have a higher BMI. By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able. This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer. 
For many bikes, battery range is more important that total power (because they're all pretty powerful). You want a bike that delivers a range long enough for your rides at the power levels you want. Most e-bikes will have three to five levels of assist kicking in anywhere from 25 percent of you pedal power to 200 percent boost. Consider how fast the battery takes to recharge, especially if you'll be using your bike for long commutes.