This question seems very engine and legal-compliancy dependent. but generally speaking the most desirable format is not always the best format in terms of distribution and execution. ideally you want lossless compressed audio for everything with minimal file-size and near-zero computation.
it's probably a good idea to simply release your pack in multiple formats.
typically music itself winds up being lossless and computationally expensive, whereas sound effects lean more lossy with much lower compute times. then you have like flac or something for archives