
Number of speakers
Learning a language based on the number of speakers is a common choice because the language which is widely spoken across various countries usually also offers more possibilities in terms of use of the language.
In this regard French and Russian are the seventh and eighth most spoken languages with approximately 267 and 258 million speakers. Thus, both the languages are widely used in different parts of the world.
Geographic importance
Geographically in which area a language is spoken would also be a major deciding factor. If you are travelling or planning to stay in any of the countries where French is widely used, French is a practical choice. On the other hand, if you plan to study or live in Russia or any of the Slavic countries, Russian would be a better choice.
Career
Growth in career is an important factor that people look at when learning a new language. Both French and Russian are among the official languages of the United Nations. However, French is more widely used when compared to Russian in many international organizations.
Russian could be your choice if you are looking for a career in Space, oil and gas or science and technology.

Ease of learning
If you are planning to learn a foreign language for personal reasons and have no particular inclination towards any one language, the ease of learning can play a major role in deciding in such a case.
In this regard, French is considered to be easier to learn than Russian as Russian has a different script and the grammar is considered to be difficult.
Availability of learning resources
Though both languages are taught widely, the French language may have an upper hand in this case as it is the most taught language after English and is taught almost in every country. Thus, you may easily find the learning resources suited for French language learning.
Usability
This is different from usefulness. Both French and Russian are useful and important in their own way. However, how much you use the language would make a huge difference. There could be different reasons to use one language more than the other. The countries that you visit regularly for business or personal reasons where you use the local language is very important.
You may have a French or a Russian partner and thus find more usability of the language at home.
