ABS, I would say. I would personally never use PLA, but that's just me. I've seen how it breaks down over time, which is what it's designed to do. People love it for some reason though. It's great for fast prototypes but yeesh, I would never use it for a permanent cosplay that I was spending hundreds of hours on.
ABS is very hard and durable but also easy to fill, sand, and paint, just like a styrene model kit (which is what the "S" stands for anyway).
But I suspect you'll get as many answers as people doing the answering.