1- A useful Decurion- So you can really get my feelings on the Angel's Blade in this post, but to sum that up, what we have now is pretty terrible. I keep trying to make it work. I really do. But list wise it is just too expensive. Any of the great combos push you well over 2k OR there are just too many madatory things (2 Furiosos in a 1st Co demi-co, a Dread and a Furioso or Command squad in a regular demi-co). And what do we get for it? The same benefit as the Demi-Co itself and the most useless benefit ever, Zealot on squads reduced below 1/2 Strength.... wooo. Did I mention I can get the +1 I benefit that the Demi-Co/Angel's Blade have with a Regular Old Baal Strike Force? SO the Angel's Blade is completely redundant and useless, clogged with too many mandatory units. Also, outside of the Demi-Co and DC SF there is no way to take a Chaplain.
Now I am not saying I want free transports. Far from it. That has been done. What should be done is
-Leave the +1 I on the Demi-Co
-Remove all the mandatory dreads
-Add a cool regular assault marine formation with some sweet benefits
-Make it so two demi-co give you Obsec and Rage (or +1A if you already have Rage)
2- A "Conclave"- Librarian, Chaplain or Sanguinary Priest. Every thing else has these trios going on, particularly with the new Triumvirates. While a Librarius conclave would be most appreciated, this is an awesome opportunity for something unique. I am not sure what a Chaplain or SP conclave/triumvirate/brotherhood would do or be, but some stat or USR sprinkling, improved FNPs, things like that would be welcome and new. If a librarius one, I would hope Mephiston isn't mandatory. Still, some sort of small character super squad with stacking buffs is the way of the future, and BA currently are in the past and keep needing to borrow loners from SM. Now that Chapter Tactics cannot stack at all, this is even worse for the codex.
3- Another flyer- Either one someone else has or a new design. For being Angels, we sure have little in the ways of Air Support and could use some more, especially after everyone else stole ours. I mostly would like the Storm Talon, however some new form of Gunship or Assault Craft would be nice. If you want to read me wax poetic on the subject, read this salty post.
4- Assault Marine Troops- Why is this not a thing. Why? AND DON'T YOU DARE SAY "THEY DON'T HAVE ENOUGH! That is the worst argument ever? Why- well they have more assault marines than Scouts! Troops is a battlefield "Role" not a battlefield quota anyway. It is about employment of the unit. Its why Dark Angels can take Terminators and Bikes as troops and why White Scars (or any chapter with characters on bikes I guess) can take bike as troops. And that is what is the worst about this: any SM faction outside BA can do fancy troop manipulation, getting some sort of better, fluffy characteristic unit into that slot. When ever I make a list, I feel like I am just wasting points on tacticals and scouts. BA are an in your face assault army. Why oh why am I wasting my time with boring non-assaulty units? A better decurion could go a long way to fixing this. Anything to make the troops more assaulty. But the fact few BA actually take assault marines is pretty sad. Especially since they are the truth in 30k.
5- Land speeder storm- This is kinda a personal wish list thing, but it would be great to have. If I am going to be forced to repeatedly take scouts, at least give me an open-topped vehicle that they can assault from! This would instantly make our scouts the best scouts there are and a decent troops choice. Especially when you equip locator beacons/teleport homers...
Honorable Mention- Beef up Mephiston, make him a LoW. Downgrade Seth to an HQ as is. Just my 2 cents. Better reflects their fluff power as well.