I'm late to this discussion, but I want to cast a vote for
kabocha (sometimes called buttercup, I think).
I like squash in general, but kabocha is the queen of cucurbits as far as I am concerned. I eat it plain and unseasoned because it is so sweet and delicious.
Easy to cook, as well. I either put the whole thing in the oven at @ 400 (no reason for that number, use your own judgement), or else I microwave it for a few minutes to soften the shell.
If I bake it until it is soft all the way through, that's all it needs. Cut it open, start eating. The seeds are good too.
If I pre-microwave it, it's easier to cut up and steam.
In terms of texture, steamed can be starchier and slow-baked is creamier. Your choice!
My second favorite is delicata, also sweet. Also easy to cook. I just put it in the microwave for a few minutes until it sort of collapses and is soft all the way through. I think it has a faintly vanilla taste.
If you want to make more effort than bake, nuke, eat, the cooked squash can be added to soups, used in a curry or stew, or any other way you use a starchy vegetable. I like to make squash tacos, with a warm soft tortilla and some salsa.
I usually ignore Thanksgiving, but this year I decided to honor Native American farmers, and eat only foods that they cultivated. I used corn, beans, squash, sweet potatoes, tomatoes and potatoes to make a big starchy bowl of veggie stew. I cheated a bit when I added turmeric, but nobody's perfect
.