I'd move the big 4 stage races (PN, TA, CDD, TDS above the other 3 WT stage races). Those are basically the monuments of week long racing
Monuments of week long racing... It's always changing.
Tirreno for a long time was pure Sanremo preparation, prestige nowhere near Paris Nice. It still has some MSR prep characteristics, but has become much more its own race, with that comes the prestige, which right now basically is equal to PN, unless you keep the history in mind.
Catalanya on the other hand has a much longer history. With many of the other week long spanish races dying out, the other catalan race Setmana Catalana too, it has somehow gained importance,(it was always more important than SEtmana Catalana of course) but with changing dates maybe a bit less? While TA and PN have the full field, Catalunya with the north in full swing has to deal with a lesser classic field. Right now seems below Tirreno, but overall I'd rate it equal really. Same for the Basques. AS for Romandie, it has lost a bit of its Giro prep race, many used to be there, now almost nobody shows up.
For me ok to rate them all equally, but if we really need to separate them I'd think Paris-Nice and the Tour de Suisse (for historic reasons, the quality has been below the Dauphiné for a while now) are above the others. With Romandie maybe as number 7?
As for 1 day races, yes, I rate Gent Wevelgem, the Flèche Wallonne above the ITTs. Strade Bianche haven't thought about it, but it's getting there for sure. Amstel and San SEbastian, as long Pogacar and Evenepoel winning gives prestige to the race and not the other way around... they are nowhere near Gent and the Flèche! Below Paris-Tours. Which is suffering due to ASO and UCI weirdness. but 20 years ago IMO was closer to the monuments then any other race.