Which visa and which country to apply for?

If the business meeting were not happening, would you be going to the Schengen area anyway? If so, you can say that the main purpose of your trip is tourism, and the main destination is France.

If you planned the trip for the business meeting, but decided to add some time at the beginning so you could travel in France as a tourist, then the main purpose of your trip is business, and the main destination is Spain.

This follows from Article 5 of the Schengen Visa Code, which says, in part:

Article 5

Member State competent for examining and deciding on an application

1. The Member State competent for examining and deciding on an application for a uniform visa shall be:

   (a) the Member State whose territory constitutes the sole destination of the visit(s);

   (b) if the visit includes more than one destination, the Member State whose territory constitutes the main destination of the visit(s) in terms of the length or purpose of stay; or

   (c) if no main destination can be determined, the Member State whose external border the applicant intends to cross in order to enter the territory of the Member States.

(emphasis added)

It is unlikely that anyone would ask you to prove that the business meeting is or is not the main reason behind the trip. In this case, therefore, you can probably choose whether to apply to France or Spain, whichever is more convenient.

To respond to your comment:

Thanks for the response. The application form asks for the main purpose of stay, I am not sure if I should fill "Business" or "Tourism", given that I am not really travelling to France for business purposes(Spain is where I have the business meetings)

When you submit a Schengen application to the French consulate, you should list the main purpose of your stay in the Schengen area. So it is, in theory at least, perfectly acceptable to say that the main purpose of your visit is business even though you will not have any business activities in France. This would be perfectly reasonable for some itineraries, but in this case it might suggest to them that your main destination is Spain, as outlined above. If they come to that conclusion, they will return the application (along with the visa fee, but probably not service fees) with instructions to apply with the Spanish consulate.