If you have 100 Mbit/s internet then its not . The theoretical speeds of b are up to 11 Mbit/s (expect 8 to 10), g is up to 54 and n is up to 300 or 400, however you need multiple antennas to get that kind of speed.
Overall, if you want to move huge amounts of data over your wireless network, get wireless n, and if you have internet from let's say 30 Mbit/s and over I'd get n as well.
But if you have the usual internet speeds like 10 Mbit/s then you're fine with b/g.