Skill level necessary to clear HW MSQ content

[Iscah]

For someone new to EX, which one do you recommend to start with, Garuda, Leviathan, Ultima Weapon or Thornmarch?

I won't start any of them until I can both consistently run these story primals and fix my gear problems in full.

...EX primals are not "story primals".

Are you sure you're talking about EX primals? Or MSQ Hard primals?

[Townowi]

I may be willing to settle for one or two extremes per xpac but I'd rather be running the extreme(s) that provides the best gauge for the following xpac. For obvious reasons, synched is a much better gauge than unsynched regardless of the extreme that serves as a gauge.

That said, which ARR extreme(s) is most representative of HW readiness? If applicable, answer healing first and DPS second: pick only extremes of primals that were previously fought in the MSQ.

And I would also like to know which HW and SB extremes are most representative of SB MSQ and ShB MSQ respectively.

Maybe I am wrong but using EX primals as gauges of xpac readiness also imply dungeon readiness for the same xpac that EX is a gauge for. That's why I kept quiet about dungeon readiness.

...EX primals are not "story primals".

Are you sure you're talking about EX primals? Or MSQ Hard primals?

To clarify I really mean that I shouldn't start running EX primals until I get the corresponding MSQ hard primal down consistently and resolve my gear issues.

[MrThinker]

That said, which ARR extreme(s) is most representative of HW readiness? If applicable, answer healing first and DPS second: pick only extremes of primals that were previously fought in the MSQ.

And I would also like to know which HW and SB extremes are most representative of SB MSQ and ShB MSQ respectively.

Maybe I am wrong but using EX primals as gauges of xpac readiness also imply dungeon readiness for the same xpac that EX is a gauge for. That's why I kept quiet about dungeon readiness.

If you are talking about synched... then like has been said before, literally none of the EX trials, across all the expansions, are representative of the difficulty encountered in dungeons and normal trials within the next expansion along. The ARR extreme trials are harder than anything the normal HW story throws at you, the HW extremes are harder than anything the SB story throws at you, and the same holds true for SB Extremes and and the ShB story.

[MistakeNot]

That said, which ARR extreme(s) is most representative of HW readiness?

None of them. Or all of them. The ARR EX-trials are harder than any of the non-EX, non-Savage content in HW.

If you want more practice before starting HW content, then forget all about EX trials.

Instead run, for example, the following standard dungeons and trials from ARR:
Aurum Vale
Keeper of the Lake
The Navel (Hard)
Thornmarch (Hard)

Most of those are required to finish the ARR MSQ anyway, and if you can handle all the mechanics in those - then you have the skills needed for HW.