buying first digital music, help....

ok, an old band i love, has an EP in only download, digital whatever....they offer :

In your choice of 320k MP3, FLAC, AAC, OGG Vorbis & ALAC

I use apple iTunes to import my cds and ripped LPs"to cd.
i imported most at AAC, years ago, as i didn’t know any better, the past couple years, I’ve been using apple lossless? i think its called.

of the multiple choices above which is compatible with apple tones and has the best sound,.
granted, its not some magical sounding band, but i do like quality to whomever i listen to.

thanks for your help.

In your choice of 320k MP3, FLAC, AAC, OGG Vorbis & ALAC



also, how do i get the music once downloaded to my iTunes library??