I haven't actually ranked all of the holidays, but Thanksgiving, for me, ranks high among them. Mainly because it is a simple holiday.
It is celebrated simply by sitting down with your friends and/or family, consuming a ridiculous amount of turkey and stuffing, and feeling thankful for all the good things in your life (which often includes the friends and family you're eating the food with).
There are no religious, or nationalistic overtones, and no one feels the need or social pressure to buy gifts, beg for candy, or send "greeting cards". Its just pure unadulterated thanksgiving. Even folks that do not have a tradition of celebrating Thanksgiving can easily get behind the idea.
If I was a sentimental man, the beauty in it's simplicity would bring tears to my eyes. Since I am not such a sentimentalist, I choose to celebrate with this Ron Swanson meme:
It sometimes surprises my American friends that Canada also has Thanksgiving, and its celebrated pretty much exactly the same way as in the United States: Friends, family, and a ridiculous amount of food. The only difference is it tend to include less football afterwards, and it happens in October. Otherwise, pretty much the same deal.
Since we now live in the United States, my family and I celebrate Thanksgiving with them (it is only polite, and lets face it, southerners can cook up a fantastically delicious turkey).
So for all my friends out there in blog land, regardless of your faith*, nationality, traditional backgrounds, or hockey fan status, I wish each and every one of you a very happy Thanksgiving.
Now, please pass the stuffing.
* Unless you are a Nihilist, in which case the most appropriate thing I can say is "meh"