The best replacement for futon is sofa bed.

The best alternatives to futon are rated as following:
★★★★★  sofa bed
★★★★  bed
★★★★  mattress
★★★★  daybed
★★  sofa
★★  couch
★★  sleeper sofa
★  sofa sleeper
★  air mattress
★  pull out couch
★  click clack
★  twin bed
  sleeper
  pull out
  spring mattress
  innerspring
  small sofa bed

Your alternative for futon is not listed? Suggest!
Speaking about futon, one probably shouldn't forget about bunk bed.

Other search terms related to futon and their ratings are:
★★★★★ bunk bed
★ bunk
mattress included
You have in mind a companion for futon and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of futon in all years. Click on graph for more.
futon
sofa bed
bed