When you want to express your admiration or appreciation for someone or something, "sing the praises of" is one of the commonly used idioms. However, there are many other expressions you can use instead of this phrase to avoid repetition or to add variation in your language. "Speak highly of," "extol the virtues of," "applaud," "commend," "laud," "rave about," "eulogize," "celebrate," "glorify," and "praise" are some of the synonyms you can try. Each has its own nuances and strengths, so choose the words that suit your context and convey your emotions effectively.