Which ip class the best for installing 284 computers on a single ip network?

Any IP class will work fine. For Instance if you are on a class B you can have 65,534 computers per network and you have 16,384 networks possible. That is a max possibility of 1,073,709,056 computers on class B network. On top of that their are 6 versions of internet. IPv1, IPv2, IPv3, IPv4, IPv5, IPv6.