My favorite binder to browse through is my FA Supporter & Character Rare binder. 
I also like looking at all the painted altered/extended Base Set Pikachu artists made for me.
But apart from those, I’m not sure what my favorite page would be. 
Some that come to mind:
All nine raw Moltres WotC promo artwork variations:
Some cool square cut and miscut Pikachu:
XY-P Pikachu promos (the blank spot is where the Organized Stamped 175/XY-P would be, but it’s in my graded binder as PSA-10 instead):
And although I’m not that big of a fan of Rainbow Rares, this page does look pretty cool nonetheless:
Greetz,
Quuador