I think part of the problem with "homo" is that a lot of people may feel it excludes lesbians. Depends on how you define homo - it means one, but it also means man in some languages - I remember discovering that while writing an essay a while ago on fatals. While Gay includes lesbians and homosexuals, it does not include bisexuals or those within the transgendre community.
Harvey Milk in the film Milk sort of left out transgendre, lesbians and bisexuals or the film makers did. Actually transgendre and bisexuals get kicked by both sides - gays/homosexuals and heterosexuals.

Queer...includes people who may fall into fetish and not be bi, gay (lesibian and homosexual) or transgendre - which may be some people's difficulty with it. But Masq's correct it is the most inclusive.