I am holding back until these are implemented or fixed.
1. An option to ignore the main quest and create my own kingdom regardless.
2. A proper way to propose peace/declare war via kingdom screen.
3. While being a vassal, they never seem to care much to defend cities/castles. Even if they do, they are always one step too late. This needs to be looked at.
4. My favorite kingdom is Strugia but their land is so widely spread out that it's very hard to defend. The map needs to change a bit.
5. Persuasion system seems to be utterly broken.
6. When you form your own kingdom and manage to persuade a clan, they just leave a minute later if not given a fief pretty much right away. This started to happen in 1.4.0. In previous versions, they stayed on no matter what.
7. Your companion parties are too stupid. And I don't like how they just wait for you to pick them up in remote places once escaped from captivity. This especially sucks during war time. Can't be traveling around for minutes.
8. The first leadership trait which trains troops appear to be either too weak or broken. This needs to be fixed ASAP.
Optional stuff I'd really like.
1. An ability to name my own kids.
2. An option not to have sex with spouse, effectively ending any chance of pregnancy.
etc. Above is all I can think of right now.