In Minecraft, there is more than one type of ice. Each is different from the other in some ways and is similar in others. However, when it comes to the ice that is the fastest, it is undoubtedly blue ice.
Mobs and players can slide much faster on blue ice than on the packed ice. Not only are they able to slide fast, but they can also slide a lot further on blue ice. Also, items within a water stream will travel faster on the blue ice. All this makes blue ice the fastest ice in Minecraft.