My three broad things:
1) Tanking. I love that we have a trait line for it, and I have fun doing it. However, the Leader of Men trait line just feels disconnected and weird. When Rask revamped it, I feel like (for whatever reason, probably just time constraints) he only took it half way. It's got odd utility traits and set bonuses mixed in with the tanking stuff. It's not bad, but it's not synergistic. I don't feel like I'm building up toward something coherent when picking my LoM traits. Not like LtC/HoH where everything reinforces one main theme.
2) Legendary Traits. Specifically, I have bones to pick with IDOME and Fellowship-Brother. Questions of strength aside, my main issue with them is philosophical. They're both mechanically strong but boring. They don't create gameplay. Oathbreakers create gameplay; people see those lovely blue ghosts pop up, and they know that it's time to unload everything they have. It's super cool. If nothing else, it gives me something to yell out in raid chat. SotD doesn't have quite as much visual impact, but it's still something we think about using, something that keeps us engaged in the fight and watching what's going on so we know when and where to apply it. Legendary traits need to feel like that.
3) LI Legacies. I hate buffsticks, and I've probably wasted enough words on them over the years. Similar to my point above on legendary traits, they're just not fun. Buffsticks are tedious bookkeeping, not gameplay. But there's more to our LI situation than just that. It's easy to build a healing emblem. But a DPS emblem? Tanking emblem? Those come down to relic choices, not legacy choices. We don't even have tanking legacies, for one thing; I mean, sure, Defensive Strike Armour Buff, but that's really it. No threat legacies, which we really need. No other survivability legacies. As for DPS, we do have some decent legacies on our weapons, but nothing on our emblems. Probably by design, but I think all of us would like the option to build different kinds of weapons and emblems instead of being pigeonholed to only having DPS weapons and only having healing emblems.
There are dozens of other things I could probably think of, too, but for me these are the three main ones.
Really, though, if I could give just one single piece of advice, it would be this: Whenever we make a build choice, that choice needs to create new gameplay, not just make numbers get bigger. The problem with passive numerical bonuses is that, no matter how much effort you put into balancing the numbers, eventually people will figure out which numbers are better than the other numbers, and then nobody will use the other numbers. But if you're adding gameplay rather than numbers, then it will almost always be valid to say, "Yes, the benefit from that gameplay is slightly better, but this gameplay is more fun/is easier for me to pull off/fits with my kinship's play style/etc. and provides almost as much benefit."
Cainwen Ciaphas, Captain of Crickhollow, HERO OF MIDDLE EARTH!!!
I will not be pushed, filed, stamped, indexed, briefed, debriefed, or numbered! My opinions are my own!