The answer to this question must ultimately be based on personal preference; however, the primary choice is between optimism and pessimism. Candide, by Voltaire, has two characters who are nearly complete opposites in their outlook toward life: Pangloss and Martin.
Doctor Pangloss is Candide's tutor, and he is the eternal optimist. In the face of every horrible (and I do mean horrible) thing that happens to him, Pangloss maintains that this is "the best of all possible worlds." Pangloss loses body parts because of syphilis, is hung (though brought back to life), and is in a slave ship until he is rescued by Candide. Each of these things happens to Pangloss because he is too optimistic to try to avoid them. Only a kind of dumb luck, which happens over and over, keeps him from being killed.
Martin is also a scholar who has terrible things happen to him: his wife robs him, his son beats him, his daughter abandons him, and he loses his job. His reaction to these things is to become a pessimist.
“You're a bitter man," said Candide.
That's because I've lived," said Martin.”
The result of Martin's cynicism, however, is a more realistic view of the world than Pangloss's. It is true that Martin sees the glass as half empty, but at least he sees the glass and can avoid getting wet--something Pangloss certainly cannot do. Because of that, I would choose Martin.
I would rather have neither as a friend because Martin is too depressed and thinks very negativley whereas Pangloss believes everything is for the best and he didn't even want to help Candide when he was dying. But, If i had to chose, I would probably chose Martin because he's more experienced and I think he would help me if I were dying and he even sees through tricks and schemes. For example, he knew that the abbe was tricking Candide and that it really wasn't Cunegonde in the bed.
I would rather have Martin as friend than Pangloss. i would rather have a friend who realizes the intensity of a dangerous situation than have one who acts like everything is fine and dandy when they are actaully not.