1. The Decca audition tapes, January 1, 1962: The complete 15-song tape of their unsuccessful audition for Decca Records, long bootlegged, with five cuts finding official release on Anthology 1. This is the first studio-quality, album-length recording of the Beatles, as well as by far the best-sounding recording of the group while Pete Best was still the drummer. Among the material not to show up on Anthology 1 is one Lennon-McCartney original (Love Of The Loved) and two covers (of Bobby Vee's "Take Good Care Of My Baby" and the pop standard "September In The Rain") of which no other Beatles versions have circulated.
2. Live At The BBC, Vol. 2: Although the cream of the Beatles' BBC recordings were compiled on the official 1994 two-CD set Live At The BBC (which properly emphasized the songs they did on the radio that they never put on their official releases), enough exists for about a ten-CD box set. A ten-CD box set would be too much for all but fanatics, especially considering that the group did many songs in multiple versions on their 1962-65 BBC sessions. But certainly a one- or two-disc supplementary set could be considered, making sure to include the five covers (of Roy Orbison's "Dream Baby (How Long Must I Dream)", Joe Brown's "A Picture of You", the Coasters' arrangement of "Besame Mucho", Stephen Foster's "Beautiful Dreamer", and Chuck Berry's "I'm Talking About You") that the band never issued in studio versions while active.
3. The live Hamburg Star-Club tapes, late December 1962: Thirty songs from these tapes were issued way back in 1977, and have cropped up piecemeal on numerous tacky reissues ever since. A sanctioned compilation with all thirty songs, the few unreleased tracks that have circulated from these same tapes, and accurate, informed historical liner notes is long overdue.
4. The Beatles Christmas Album: As most fans of the group know, for every year between 1963 and 1969, the Beatles put out special flexidiscs with a five-minute-or-so Christmas message available only to members of their fan club, combining holiday greetings with sketches, bits of songs, and (from 1966 onward) quasi-surrealistic sound montages. In 1970, with the band having recently split, the fan club instead put out a full LP, The Beatles Christmas Album, collecting all of the 1963-69 flexis on one long-playing disc. Long bootlegged, this should be released officially, with outtakes from the sessions (and there are some that have already been bootlegged as well) added as bonus tracks.
5. The Complete Hollywood Bowl Concerts: The 1977 LP The Beatles Live at the Hollywood Bowl (itself never reissued on CD) drew from parts of three concerts that Capitol Records recorded at the Los Angeles venue on August 23, 1964, August 29, 1965, and August 30, 1965. All three of the complete concerts have been packaged together on bootlegs already; such a package would make a worthy official release, despite the multiple versions of many of the songs.
6. The "Kinfauns" (White Album) demos, circa late May 1968: Around late May 1968, shortly before entering the studio to record The Beatles, aka "The White Album", the Beatles recorded no less than 27 acoustic-flavoured demos at George Harrison's house, "Kinfauns", in the London suburb of Esher. In addition to including early versions of 19 songs from The Beatles, these included half a dozen songs never to be released by the Beatles while they were active, though all of these would appear in some form on some post-Beatles compilation, solo Beatles release, or (in the case of "Sour Milk Sea") a cover version by fellow Apple Records artist Jackie Lomax. A thorough compilation of all 27 (or more, if they exist) Kinfauns demos, with the best available fidelity and cleaned-up sound, would be a solid contender for the best collection of (largely) unreleased Beatles material that could be envisioned at this point.
7. More Get Back/Let It Be sessions, January 1969: Around 100 hours of material from when the Beatles were recording what was originally to be the Get Back LP, and ended up (eventually) being the Let It Be LP and film, in January 1969 have been bootlegged. It would be too extreme to officially release all of this, but an additional CD or two would certainly be possible. This could take the shape of the entire January 30, 1969 concert on the rooftop of Apple, from start-to-finish, and/or one or two discs of the best alternate/unissued takes/rehearsals that have yet to be blessed with commercial availability.
8. Anthology Vol. 4: Although the three two-disc Anthology volumes did cream off the best previously unreleased Beatles material in the 1990s, there's enough for an additional, fairly solid one- or two-disc set. Click here http://www.richieunterberger.com/bestubeatles.html for a sample set of thirty 1962-70 tracks that could fit onto one 78-minute disc.
CD or MP3? At mojo4music.com the answer is "vinyl".