The Hatch is one of the most popular noise machines for babies. I also use this LectroFan noise machine for myself. I have never had an issue with either just randomly turning off.
What we use Adaptive Sound Technologies LectroFan Premium White Noise Sound Machine with 20 Unique Non-Looping Fan and White Noise Sounds and Sleep Timer, White, unscented, 1 Count https://www.amazon.com/dp/B00JU8P8VY/ref=cm_sw_r_cp_api_i_EVSFRQQ7CXGNS2N51YK8
The twins sleep great with 2 in their nursery!
My husband and I have had this one for close to a year. It's surprisingly tiny, but gets really loud. We don't usually have the volume all the way up. It's nice because you can easily adjust the tone and type of sound. It also (unlike many sound machines) doesn't run on a loop, so I've never experienced the weird thing with some sound machines where you start repeating noises, which drives me bananas.