The Indy 500 vs. F1 Monaco GP: Which is More Prestigious?

Both the Indianapolis 500 and the Monaco Grand Prix are iconic races held on the same weekend in May. Both have tremendous history and prestige, but which do you consider the more significant achievement for a driver to win? Has the relative importance of these races changed over time?

I have some thoughts on this topic. I disagree with some points here. What do others think?