My father uses an NAIS EW273CD (today PANASONIC, purchase about 2000 ?, no longer exists), I have offered here BOSO Medilife S (2006), and because a device has been forgotten in the meantime times on vacation, most recently, the current ' Stiftung Warentest 'winner PANASONIC EW-BW10.
The measurement results are almost the same with the people using the various devices, ie it will be displayed with the different devices the same readings. Cross-checks with the upper arm devices (eg friends / relatives, or at the doctor) also showed identical measurements, so that you can also start with the accuracy of the results.
I personally Favorite offered here BOSO device. It is very compact, yet easy to read and a whole very simple and easy to use. The compactness, it also seems to me to be less vulnerable to external damage - for example where there is less space for the toast, less can go broke ...
When PANASONIC in direct comparison, the display is larger (very large - do you really need that?) And it has a memo function with average. Compared to BOSO the measuring process takes slightly longer.
Considering I can the age of BOSO of now just over five years this device also certify a good life with many thousands of measurements (is still in perfect condition, is kept always in the provided box / transported).
In the end it is in my opinion a rather subjective, or even individual decision which device is now anschafft (appearance, test result, screen size, their own experiences with a brand ... Any opinion of users ... ;-).
Or which devices in the pharmacy of his confidence are currently available - if you do not want to order online.
PS: When searching for information about our old NAIS device, I've found that there are still spare parts (eg a replacement cuff) PANASONIC purpose. For whom these things represent a buying decision, which should be informed in advance about times when the respective brands.