Prestige Contest

More bottombucket stuff, but I actually enjoy this question, believe it or not. I think scarcity is actually a decent proxy for prestige here, so that's going to be my thrust. In that vein,

Most prestigious is "Head of State of a G7 country." With some quick Wikipedia searches, I've established that there are around 200 or so of these in the last 100 years (December 19, 1921 - present). I used Prime Ministers in Canada, Italy, France, Japan, and the United Kingdom, Chancellor in Germany, and President in the United States. So 200 - 250 of these dudes, and you've got some heavy hitters in there. FDR, JFK, Churchill, Hitler, Mussolini, etc. 

Middle in prestige is Nobel Laureate. Nobel Prizes have been around for about 120 years and there have been 962 laureates receiving 603 prizes. Lot more of these than heads of state, even controlling for the time differential. Pretty big ones in here too. Einstein, Heisenberg, Curie, Fleming, Hayek, Friedman, Arrow, Modigliani, Miller, Nash, etc.

Rhodes Scholars are the least prestigious. There have been more Rhodes Scholars made at Harvard than the heads of state, much less all the other schools. It's a great honor, just not as selective as the other ones.

Pity you don't talk about fun stuff like this more often.