For me personally Indy is the more iconic character and franchise. Overall, It’d be easier for me to pop in an Indy movie on a lazy Sunday than MM which makes it the slightly better franchise to me.
Mad Max is no slouch tho, it might be the more consistent one of the two.
Consistency counts a lot for me. I love the character of Indy more than I love everything else around him in four movies. Because I love him, I can sit through the movies and find enjoyment in all of them, even crystal skull to a degree. But I know at least three mad max movies are going to easier watches for me