Which factor should be most important if you are considering purchasing a new video game?

the number of games available for purchase
the quality of the games produced by that manufacturer
the popularity of the video game with your friends
the other things you could do with your money instead

the popularity of the game with our friends.

Explanation:

Let's examine the possible answers:

the number of games available for purchase

NO, irrelevant, there will always be more games for sale than what you will buy.

the quality of the games produced by that manufacturer

Yes, if you like how a given studio makes their games, that could certainly be a factor.

the popularity of the video game with your friends

YES. If your friends like it, there's a good chance you'll like it too, and you'll have someone you know to play the game with.

the other things you could do with your money instead

No.  You'll always want to buy other stuff as well.  Unless you're a die-hard gamer... then what else exists in the world?

So, there are 2 important factors.  The most important being the popularity of the game with our friends.

The quality of the games produced by that manufacturer

Explanation:

All the factors listed out are factors that are to be considered if you are to make a new video game purchase but the most important is the quality of the games produced by the manufacturer.

while the quality of games produced by the manufacturer is most important is because no one likes to purchase a low quality video game with their hard earned money so that is paramount before other factors like the popularity of the video game with your friends because it is possible your friends might not like exactly the kind of game you like and considering other things you could do is not really suppose to affect you decision on the type of game you are purchasing but it is considered in cases when you are short on cash to purchase a game.