The best replacement for formaldehyde is paraformaldehyde.

The best alternatives to formaldehyde are rated as following:
★★★★★  paraformaldehyde
★★★★  formalin
★★  glutaraldehyde
★★  aldehyde
★  formamide
★  urea formaldehyde
★  no formaldehyde
  methylene glycol
  paraformaldehyde fixation
  pfa
  formic acid
  formaldehyde resin
  phenol formaldehyde
  toluene

Your alternative for formaldehyde is not listed? Suggest!
Speaking about formaldehyde, one probably shouldn't forget about potassium permanganate.

Other search terms related to formaldehyde and their ratings are:
★★★★★ potassium permanganate
★★★★★ grignard reagent
★★ resorcinol
★ tollen's reagent
urea
You have in mind a companion for formaldehyde and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of formaldehyde in all years. Click on graph for more.
formaldehyde
paraformaldehyde
formalin