Mules were mainly worn by 18th-century women with a kitten ... mules both a comfortable choice. Comfort is the main reason for people prefer these types of shoes for indoor and outdoor settings.
But whether to go for slippers or loafers, trainers or slides, ballet flat or mule, is up to you. True comfort can be found in the sheepskin lining of a slipper but putting a (real) shoe on might ...