I know this seems like a weird topic to talk about, but last autumn I discovered velvet hangers after using plastic and metal ones before, and I can safely say I'm now totally converted. Just yesterday I picked up another set, so now there are no other than velvet hangers in my wardrobe. The best thing about these is that they're not slippery at all, so clothes stay put and don't fall to the bottom of my wardrobe. They're also quite thin, so they don't take up too much space, which is important for me, as my section for hanging clothes is really tiny (although big enough for storing my obsession with white shirts and black dresses).
However, if you haven't tried velvet (or maybe other non-slippery) hangers yet, you're missing out big time, so go and do give it a try.