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Strictly from rules standpoint I do not recommend WB. They are literally just slightly worse regular SM (from the index, not from codex astartes). They are slightly (very slightly) better at summoning, but that is it. Every other legion is as good or better at what WB is supposed to be doing on the table.

That being said they truly are the most CSM like CSM force in the game, the true vanilla CSM even though BL commonly has that title.

All in all the legions do not vary that much on the table. You can make do with what ever you choose. You just have to play the trait (or in the case of WB the practical lack of one) and that shows on the list you are making. So, here are the styles of play as far as I see them.

Black Legion is focused on steady advancing. They can move, advance and still shoot their rapid fire weapons as assault weapons. This means that you can really even run your terminators if you want to. Abaddon makes stuff "close" to him ignore morale.

Alpha Legion is -1 to hit if they are 12" or more away from the enemy. You essentially want to either keep that far away from the enemy or go straight in.
Their warlord will live as long as you have characters alive...which is good.

Iron Warriors are the anti fortified position specialists thanks to ignoring cover. With 8th edition compliant terran (about 2x what was used in 7th) this is good. On a planet bowling ball this does nothing.
Their warlord also makes things near him fearless.

Night Lords use morale manipulation. The small unit large scale opponent withering force in melee (opposite of WE which just kills the thing it touches) thanks to morale shenanigans making it a lot more hazardous to face these guys in close combat. Outside of that they do nothing.

Word Bearers have a slightly better summoning ability provided you have CP to use their stratagem. Other than that they really are just "plain emomarines" without advantages or drawbacks. It is noteworthy though, that summoning is more of a liability even for WB in matched play. In narrative this is the best undivided legion, no questions asked, just because they can summon things pretty much without risks and free units are free units...

Renegades (not a legion but still) is the long distance melee threat "legion". They can advance and still charge. This is equal to an average of 17" charge range (6" movement, 3"-4" advance, 7" charge).

My 2c. Pretty obvious stuff. The main point is that you should not trust the WB legion trait since it really does not help with morale issues that much...or at all mostly.