The best introduction to (the UK) Nirvana is their greatest hits 'Travelling On A Cloud'. (Failing that, buy 'All Of Us', which is probably their most typical album.)
The reasons why this is not the best introduction: on this CD -
Track 1, the mono mix, is great for collectors and completists, but it's more of a demo with a Vienna Boys Choir backing vocals and spartan instrumentation. Interesting, but it's not the 'real' track with full orchestra and no obvious heavenly choir.
Track 5, Rainbow Chaser, is a pretty awful funked-up rockier version of the better-known, slower tempo, phased hit single classic.
The rest of the choices are uninspired, so for that reason I'm giving 3 stars to a 5-star band.