This is what I have used, it's Fire Resistant & Water Repellent and Reduces Sound. It won't drop or sag over time either.
The Home Depot
ComfortBatt 5-1/2 in. x 15-1/4 in. x 47 in. R-23 Fire Resistant Stone Wool Insulation
https://www.homedepot.com/p/ROCKWOOL...972546?cm_mmc=[*Campaign*]|[*CampaignID*]|[*AdgroupID*]|[*TrackerID*]