Spring. For some reason the Francie cameo excited me more than anything else.
It was just really unexpected.
Paris lecturing the students at Chilton and all of them running out crying was perfect. Very old-school Gilmore Girls right there. I also loved Luke going to look at that restaurant with Emily and that woman. The part where they're talking right in front of the owner about what will happen to his business.
"He won't have a pot to piss in."
Every time Miss Voodoo is asleep Shelly walks hard as beep and it wakes her up.

Yes, for me, Spring and Summer are awesome. I loved the start of Summer, and the "These boots are made for walking" Sequence.
But then again, Fall was awesome too.
If I had to pick one, though,
Spring
. For sure. The only time I actually felt the old Rory and Lorelai was at the end of this episode in the Hotel.