Black Carbine bearings are the least expensive. They are suitable for the tri weights in bearings. Not recommended for center bearing.
Stainless Steel, this is the kind of bearing most spinners come with standard. It is a quality bearing with good spin time.
Hybrid Ceramic and Steel Bearing. This is ideal for center bearing of most fidget spinners. It has ceramic balls encased is a steel housing. It offers above average spin times and smoothness.
Full Ceramic bearing. This is the best available bearing for the center bearing of your standard sized fidget spinner. It has ceramic balls in a ceramic housing. This means very low friction and superior spin time, and smooth spinning.