I also believe on a single lap, Mika is the fastest of his time in F1. Even quicker than Michael.
I think Leclerc is probably the best qualifier on the grid, which I don't think I'd ever have said about Alesi or Arnoux.
I think my previous post is still a valid response to these.
I've previously compared Leclerc to Hakkinen in my own mind (with Verstappen as Schumacher as Spillage says). It think it's quite good because some people would claim that Hakkinen was the better qualifier like they do with Leclerc now. But this was based on cherry-picking, looking at Hakkinen/Leclerc's best laps, rather than how they perform over a whole season. Schumacher would have had a much better qualifying head to head against Coulthard than Hakkinen would, and Verstappen would over Sainz. Whether the absolute best of Hakkinen/Leclerc was/is better than the best of Schumacher/Verstappen at qualifying is a different question to who was/is better at qualifying, and it's also far harder to judge, as it's even harder to subtract the car in a one-off than it is over time.
I also think another possible analogy is Montoya, although I'd definitely rate Hakkinen and Leclerc above him. But there was a time when some people thought Montoya was the best qualifier in F1. This probably peaked with his five consecutive poles in 2002. But over the season, his head-to-head against Ralf wasn't much better than 50/50.
By the way, I noted in my head that last year at Baku, Sainz was actually quickest after the first runs in Q3. If he'd had the same luck with the red flag that Leclerc did in 2021, he would have had an equivalent pole. Leclerc was lucky at both Monaco and Baku in that respect, and Monaco was actually was actually Leclerc's own crash. So I do think circumstances have played their part in the making of the Leclerc legend.