Which is the 'must have' of the 4 new soldiers?

[rexscarlet]

The "Mule" just so I can scratch build;

https://www.thewrap.com/wp-content/uploads/2015/08/Monty-Python-and-the-Holy-Grail.jpg

[archmage45]

Or you can just get Oswald from Reaper!
http://www.reapermini.com/OnlineStore/oswald/latest/77141

[Fencing Frog]

I was a little disapointed with the new soldiers.  If I start over with a new 1st level warband the Javilier will fill out the Thug slots.  I was excited about the Crow Master but frankly he seems to expensive for what he does, 200 gp just to get started(with the base upgrade), he's the same price as a 1st level Aprentice, but less capable even with the Crow as an "extra" member of the war band.

The Bard he's potentialy handy... depending on your oponent, most of mine don't use mind effecting spells.

The Mule is very helpful especialy for certian wizards, like those who brew more potions then then can use from game to game.

[Awesome Adam]

Like you mentioned, I really see the Javilier as a starting warband kind of guy.

The Crowmaster I see as the later game upgrade for a warhound. The crow and the warhound fill the same role, a fast, expendable, model to harrass your enemies that also allow you to exceed the warband limit.