A personal development perspective is probably a more interesting way of doing this:
1972-3: T. Rex. I was age 9. I also bought some Slade records.
1974: Discover ‘prog rock’ in friend’s big sister’s record collection: Floyd, Yes, ELP, Tubular Bells etc.
1975: Finally figure out A Nice Pair is her best album.
1976: Discover Hawkwind, Man, Kraftwerk, Tangerine Dream. First gig, T. Rex, at New Brighton Floral Pavilion.
1977: Punk happens: buy Sex Pistols singles and NMTB and hide under carpet so mother can’t find them. Devo singles too, but no need to hide them.
1980: Factory / new-wave, etc. I see The Fall, ACR, Teardrop Explodes, Echo & The Bunnymen etc live – this was an important year as it was the point I really grasped that this stuff was ‘doable’. I bought a bass.
1982: Discover modern classical via a girlfriend who was a music student: Stockhausen, Cage, Webern etc.
1983: Industrial stuff e.g. TG, Foetus etc along with indie, Smiths, Cocteau Twins etc.
1986: US stuff: SST, Sub Pop, Sonic Youth etc plus minimalism, Glass, Reich etc.
1987: Techno, baggy, Madchester etc. Also discover some of the ‘missing’ bits of Krautrock by stumbling on Can’s Ege Bamyasi album.
1989: I discover jazz with the Blue Note 50 year anniversary comp. One of the most important records I’ve ever bought.
1993: Warp Artificial Intelligence series etc.
1996-onwards: Post-rock, Arab Strap, Mogwai, Sigur Ros / freak-folk etc.
These days I just buy across all genres and all time periods in a largely opportunistic way based on what’s in the rack in front of me at the time.
Tony.