It probably has the best coverage in the world. Cross chop, wild charge, ice punch, earthquake, stone edge, etc. So much to chose. It patches up an electric weakness with motor drive and also gets a speed boost from it.
It can trap the plethora of defensive steel types with magnet pull. Then it can spam charge beam boosts and get amazing stats. Flying types can absorb its ground and fighting weakness and the flying type's rock, ice, and electric weaknesses all get blocked by magnezone.
they are both great but I would choose magnezone.