Describe Existentialism Philosophies of Marcel vs Sartre.

In his article Testimony and Existentialism, Gabriel Marcel argues that we need to practice a testimonial attitude that allows for “recognition and gratitude.” He sees our existence as indebted to others and speaks of “our capacity to open ourselves to others.” Explain Marcel’s philosophy and compare and contrast it with Sartre’s existentialist philosophy as exemplified in his play No Exit, where it is argued that “Hell is other people.” Whose view do you find more convincing and why so?