[jval43]

Unironically Mac OS 7/8/9 felt the best IMHO. Even though there were some missteps (the https://en.wikipedia.org/wiki/Control_Strip was awful) and 9.x got a bit overloaded towards the end.

Mac OS X (and macOS still) never felt as good.

[musicale]

Apple's classic human interface guidelines were well thought out. They should consider (re)reading them sometime.

[BoredPositron]

Tiger was fine :D

[mikepurvis]

A lot of people argue it peaked with snow leopard; that was consistent, performant, and feature complete, not yet overly influenced by mobile.

[dialup_sounds]

Tiger still had that weird thing where half the apps were brushed metal for no apparent reason.