When it comes to keeping the mast up, stainless-steel wire is still the most popular, though many sailors now are looking at the pros and cons of rod rigging. Rod is lighter and stretches less, though it's more prone to fail without warning. It is also impractical to store spare lengths onboard. For those married to wire, for bluewater use swage terminals are giving way to compression fittings that can be assembled with hand tools and disassembled for inspection. The carbon-fiber wave is still gathering momentum.
Carbon is now de rigueur in racing and is increasingly common in larger performance-cruising rigs.
Carbon masts are expensive, however, and the overall weight savings may not be as great as you expect, once the new mast is fully dressed. Blocks and leads. Carbon is making inroads here, too. Racers can't afford to ignore the weight savings, and even cruisers are rethinking how they run lines on deck. Leading too many lines to one place can be just as inconvenient as going to the mast.