I have only seen dry-pipe water systems lately, since halon is long gone.
I did see one system that used HI-FOG sprinklers. Smaller water droplets are supposedly able to extinguish a fire with significantly less water. You're still sad, but maybe you can salvage more equipment.
I've seen a few chem agent and inert gas systems, but only when someone realized cost of equipment + loss from downtime > cost fire suppression system, which is less often than it should be.
dry pipe systems are probably the most common though.
