A subjective question, but in your opinion which decade since 1900 saw the biggest leap forward in cricket compared to the one that preceded it? You can take anything into account including playing standards, playing conditions, law changes.
I'll throw the 90s into the mix. The 80s were dominated by the WI. Aus were poor. There were only 7 Test teams etc. The 90s saw the rise of Aus and the challenge with WI in the mid 90s. Pakistan were exciting. There was the reintroduction of South Africa. Coloured clothing in the WC. Shane Warne bringing leg spin back to the back pages.
To me, and perhaps because I grew up in the decade, the 90s saw a massive improvement on the 80s.