The best replacement for duvets is comforters.

The best alternatives to duvets are rated as following:
★★★★★  comforters
★★  coverlets
★★  coverlet
★★  comforter covers
★  quilts
★  blankets

Your alternative for duvets is not listed? Suggest!
Speaking about duvets, one probably shouldn't forget about matching curtains.

Other search terms related to duvets and their ratings are:
★★★★★ matching curtains
You have in mind a companion for duvets and it is not yet here? Propose!



Google Trends

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duvets
comforters
coverlets