I have above mentioned Zooz and Ring Door/Window gen2 sensors.
Both never failed. Ring sensors are bigger due 2 CR2032 batteries and they last for almost 2 years, comparing to Zooz, which last around year, depending on use.
However Zooz is much smaller and you can fit it almost anywhere.
I use Ring on all exterior doors and windows, and Zooz on all interior doors, cabinets etc.
Ring Alarm Contact Sensor (2nd Gen)
Another advantage of Zooz is exterior case that they have.
I am using one of those on my mailbox box. Sensor is placed under the mailbox with magnet on the bottom of the door.
Ring has outdoor sensor for more than twice the price.
Ring Alarm Outdoor Contact Sensor
Ring zwave sensors look good, as they are more readily available for me at a decent price.
Will the upcoming Smartthings change to Edge drivers cause any trouble for the Ring ones? My understanding is the Xiaomi ones will be affected because of the custom drivers.