Five Toughest R Master Sets

Here is another one of my Top 5 Lists. So here goes:

1. US Caramel Presidents - Imagine trying to get McKinley in all the color variations (And 3 of them exist - don't know about the rest).
2. Sea Raiders - I'm starting to think that the Map Card is scarcer than WW No. 25
3. Wild West - mainly due to No. 25
4. Indian Gum - S288's lead the way.
5. G-Men & Heroes of the Law - Any comments here Mark?

And an honorable metion to Fleer Cops & Robbers.

I'm close on Master Sets for Nos. 3 to 5. So any comments or opinions? I'd love to hear any input.