Hang on, I forgot something.
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It's a dead heat between Throwing Muses' and Tindersticks' eponymous debuts.
https://m.youtube.com/watch?v=fKRfWcRZpYM
https://m.youtube.com/watch?v=ReYu-qts2Dg
Both purchased on the week of release when I heard the above tracks in Max records in Eastbourne...
I'm narrowing it down to acts that went on to release several more absolute corkers, not just one or two so, no Velvet Underground, Sugar, Pixies etc.
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Anyway
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Throwing Muses, Throwing Muses wins.
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Honourable mentions to
REM, Murmer
Elvis Costello, My Aim Is True
Wire, Pink Flag...