The final decision has to be between the two of you of course, and there might be reasons why it's best for the dog to keep the tooth. Thus a root canal might be better.
But let me tell you honestly about how dogs feel about their teeth. All they want is a pain free mouth. A mouth they can eat with and bark with. They don't care if they have gaps. They don't think of themselves in a shiny-tooth beauty contest where every single tooth has to be white and perfect!
Basically once an extraction has healed a dog isn't going to care two hoots about it. All they want is no pain and to be able to eat well.
If the extraction heals quickly and naturally as it should do in a healthy dog, then they will be quite happy with that. My own dog had a tooth missing. She was fit and happy and very pretty anyway (!) and it caused no issues.
The only reason I can think of for a root canal (which may or may not be a permanent solution) would be in a case where a tooth was really very important to keep, as its removal might impact the ability to eat properly, or cause serious mis-alignment of the jaw, or in a case where there were not many teeth remaining.