Hi MattressResearchIsKey.
Great username. 
You may be interested in out mattress protector thread that has some recommendations from Phoenix.
Specifically as it relates to 5 side protectors, Phoenix previously offered these recommendations.
For what it’s worth, this is the one I use and I love it. It does a great job (and I have a baby and multiple dogs/cats to protect the mattress from!) and it really it quite soft.
You probably can’t go wrong with Nest Bedding’s own recommendation for a protector since it likely pairs best/very well with their mattresses.
I hope I’ve been able to help here! If you have more questions, please do ask.
NikkiTMU