[{"name":"1","machine_quality":2},{"name":"1","machine_quality":4},{"name":"2","machine_quality":2}]

db.collection.aggregate([{"$facet":{"global_max":[{"$group":{"_id":null,"m":{"$max":"$machine_quality"}}},{"$project":{"_id":0}}],"groups":[{"$group":{"_id":"$machine_quality","names":{"$push":"$name"}}},{"$addFields":{"machine_quality":"$_id"}},{"$project":{"_id":0}}]}},{"$project":{"global_max":{"$let":{"vars":{"v":{"$arrayElemAt":["$global_max",0]}},"in":"$$v.m"}},"groups":1}}])