Our family have always chosen to be our own celebrants for family funerals if there was no priest available who knew the deceased. Every funeral I go to which has a professional celebrant only convinces me more and more that this is how we should continue.
The main reason for that is because they are 'professionals', people who do this, if not daily, then several times a week. Those dreadful eulogies by someone who never knew the deceased, either running through the deceased's life as if it was Cv for a job application: born in (year) to (names and occupations) education (schools, O levels, A levels etc) , career, (employer, jobs, dates) or retailing second hand stories about someone they have never met.
Do not get me wrong, I know that these professional celebrants are well trained, compassionate and do have every kind of concern for the living, but it is impossible for them to speak of the deceased the way someone who knows them can.
I was almost reduced to tears of despair at the funeral of a friend a year or so ago. The celebrant, nice though she was could not even begin to comprehend just what made knowing my friend so magical, and I was not alone in feeling that, only someone who knew her could really understand her special magic and even begin to do her justice.