Vendors are jerking us around, switch stacking help. (xpost /sysadmins)

I'm no hardware guy and I'm not sure if the answer is based on the brand, but 4 vendors are contradicting each other and I'm starting to lose hope in finding a correct answer.We're installing new switches in a 7 floor building, each floor has around 4 - 5 switches running in stack configuration to appear as a single virtual switch, those stacked switches will all connected to an aggregation switch eventually. Problem is no one seems to figure out what are the hardware requirements to connect those stacked switches to an aggregation switch, I know that we need 2 SPF ports to configure stacking in a loop configuration, but what is the correct way to connect them to the aggregation switch?

1. One Vendor says that every physical switch needs 3 SPF ports, 2 for loop and 1 to be connected to the aggregation switch using a direct cable, which is totally crazy and goes against the goal of stacking.
2. Another says that all switches in the stack need only 2 SPF ports, and that I can close the stacking loop by taking one of the SPF ports in the first and last switches and connect them on the aggregation switch.
3. Another says that all switches in the stack need 2 SPF ports to close the loop, but the first and last switches in the stack needs 1 additional SPF port to connect them to the aggregation switch.
4. the last one says that all switches in the stack need 2 SPF ports to close the loop, but the first and last switches in the stack needs 2 additional SPF port instead of 1 to connect them to the aggregation switch.

I'm leaning toward answer 4, but a confirmation from one the hardware masters here with a link that I can stick it to the vendor faces will be awesome.