I think linguists would mostly agree that IPA is as good as it'll ever get. Theoretically you could start from nothing, not from any Latinate alphabet, and create a system of markings that are more, well, systematized, and end up with something that looks as foreign as Korean (which is pretty much how the Korean alphabet was made). But, then you'd have something that would feel far less familiar to most people than a Latin-alphabet-based IPA like we have now.