So I tried searching but only came up with info on stems, when what I am looking for is info on the pros and cons of the threadless steer tube sizes. Like why is the kilo tt 1" threadless over 1 1/8" threadless? Is there a noticeable difference in stiffness, strength and or performance?

also as a side question does anyone know of any classy (kinda quill stem-ish) threadless stems out there?