If Michael had had a decent narrative arc it would have been interesting to see her rise to command but we didn't get that so it seemed more like a case of right place/ right time and also, horrifyingly, let's put her in the centre seat and see if she can cope which isn't I, imagine, standard Starfleet procedure. It still rankles how Saru and Tilly were handled in S3. But even as someone who's never been a great fan of Michael, she's been okay in the centre seat, better than I expected.
Re the central question it has to be 1&2 for me. They were a mess at times and I didn't always agree with the decisions taken but the show had energy and dynamism, conflict and just general in your face'edness

By contrast the show now feels very safe and very cosy. As someone upthread says it feels like you're not allowed to have an argument with someone without being advised you might need therapy!
I'm all for exploring characters emotions and using non violence to solve issues but at times right now the show makes TNG look like Blakes 7! Are we sure the crew haven't been infected by the spores from Omicron Ceti III? At this rate I think they might need a Red Hour soon

We used to get a bit of snark from Stamets but he's joined the collective now, which just leaves Reno and we're only allowed 16.4 minutes of her per season!
Also I really miss Tilly.
And my other issue for not liking 3&4 as much is the time jump. It just stretches credulity to breaking point. It's like a Viking longboat turned up today and we not only integrated it and its crew into the Royal Navy, but made them the most important ship in the fleet. I get the spore drive and all that, but the only member of the crew you need for that is Stamets. It could have worked, either if the Burn had knocked everyone back five or six hundred years in their development, or if the crew had been able to use some kind of Krell intellect enhancing machine but neither of these things happened.
Don't get me wrong, contrary to how the above might sound I still really enjoy Disco, it just doesn't quite get my blood pumping the way it once did.