You had best post that sentence! "plus bon" is like saying "gooder" and I'm sure you don't want that. It looks like you are using the following comparisons, superlatives:
good = better = best
bon(bonne) = meilleur(e) = le/la meilleur(e)
and of course, don't forget the plural forms
However you could say "less good" = moins bon(bonne) BUT in that case I would say:
bad = worse = the worst
mauvais(e) = pire = le/la pire
When in doubt about something, please post it in its entirety. Taken out of context, we may not provide the best answer!
Sra (aka Mme)
Why do you have to replace plus bon ina sentence with meilleur, but not when you're using moins bon?
2 answers
like you can't say "Le restaurant le plus bon est...",but you can say "Le restaurant le moins bon est...".