Wire floors can be good if the correct wire is used and an alternative material resting area is also provided. Not so good if inappropriate materials are used and/or the rabbit has no place to go for relief from the wire.
Best is 12 gauge galvanized after weld rabbit wire. If you can't get it, 14 gauge works in a pinch but is less durable over time.
Always provide a piece of plywood, an EZ Floor mat, or some other place for the bunny to get off the wire if they choose.
Don't use chicken wire, lightweight hardware cloth or anything that the bunny"s foot could get caught in.