I had a few bad experiences with 9 speed, none with 8 spd so in a huff went back to 8, and I’ve been on it ever since. May have been related to the frame it was on, in hindsight but my perception was that it chainsucked far more easily.
However, just recently I have found it increasingly hard to get decent quality 8 speed stuff, particularly at good prices, and so reluctantly I think that once the existing drivetrain is finished I’ll be going back to 9 speed and hoping I do better this time.
If interested, i have a cheapish (deore I think) 11-30 cassette new and unused, an unused pair of Sram but shimano compatible shifters (not sure Rocket or attack – will check later) and will also have the used but still functional Sram shifters off the bike as well in another couple of months when this set of cassette and chain has reached its lifespan.