My dictionary uses Wade-Giles, fortunately, because bats as that one is at least I'm familiar with it. I loathe pinyin. Its arbitrary redefinition of letter sounds relates to no language that uses the roman alphabet ordinarily and is totally nonintuitive. X cannot approximate anything close to an s sound. Even the Hepburn system in Japanese has a logical explanation to it, but pinyin only makes sense to people who already speak the language. For a non-speaker it's useless.