The UA Changeling was super fun to play. The official release of the Changeling turned it into a fancy human. I want to bridge that gap while adding appropriate restrictions. Here's what I've changed:

Unsettling Visage
For just an instant, you contort your face in horrible way in order to disorient an opponent. In combat, you can use your reaction to gain advantage on your attack roll, or impose disadvantage on an attack roll against you. You must use this feature before knowing whether the attack hits or misses. The creature must be able to see your face, not immune to fear effects, and not suspect you are a shapeshifter. Using this trait reveals your shapeshifting nature to any creature within 30 feet that can see your face. Once you use this trait, you can’t use it again until you finish a short or long rest.

Yep, this fun mechanic is back. I don't know about you, but if someone's face contorted into something horrible as I'm trying to attack them it would certainly throw me off guard for a moment. It's not the super OP "Each creature within 30 feet of the changeling must succeed on a DC 13 Wisdom saving throw or be frightened for 1 minute." that the NPC/monster version has, but instead a happy compromise with a lot more failure conditions. That mindlessly raging barbarian that's immune to fear? He doesn't care what your face looks like, he's going to smash you anyway. Attacking someone from behind? They can't see you anyway, why are you using this?

Ability Score Increase
Your Charisma score increases by 2. In addition, one ability score of your choice increases by 1.

Jeremy Crawford says changlings could dump all 3 points to CHA. I'm not going to argue with that.

Shapechanger
As an action, you can change your appearance and your voice. You determine the specifics of the changes, including your coloration, hair length, and sex. You can also adjust your height and weight, but not so much that your size changes. You can make yourself appear as a member of another humanoid race you have seen, though none of your game statistics or abilities change. Your musculoskeletal structure does not change, and as such you cannot create functional wings, horns, fins, tails, etc. Your clothing and other equipment don’t change in appearance, size, or shape to match your new form, requiring you to keep a few extra outfits on hand to make the most compelling disguise possible.

Even to the most astute observers, your changed form is usually indiscernible from the race you are copying. If you rouse suspicion, or if a wary creature suspects something is amiss, you have advantage on any Charisma (Deception) check you make to avoid detection. This does not apply if you are copying an individual known to the observer.

You stay in the new form until you use an action to change your form or until you die.

There was a lot of ambiguity on the original version, and little benefit in the revised version. This clarifies that although you can change your appearance, you can't suddenly gain darkvision or flight just by looking like another species.

I also brought back the advantage on deception checks with a twist. Are you pretending to appear as a random elf to a merchant? You're an elf, why would they care? Have you shapeshifted into the King in an effort to fool his personal guard? Yeah, they're going to notice something is off, and you should not have advantage then. It allows enough wiggle room that the Actor feat would be useful.

But what about Divergent Persona? Well, that didn't make much sense to me. When you think about it, most tool proficiencies rely on specific knowledge on how to do things instead of a physical form. 

So those are my proposed homebrew changes to make a Changeling fun. What do you think?