What is considered attractive for tengku?

First off, what do tengku find attractive in other tengku?
At the most basic, tengku find healthy appearances to be attractive or at least presentable. Full even feathers without any bald or thin spots is considered a sign of good health. Shiny feathers are considered a sign of good health. Dull, uneven and overly molting feathers are considered a sign of poor health. This applies to both sexes.
Tengku also value the "aura of raven's wisdom" or the "aura of the raptor's prowess". This means that the tengku looks wise and clever or the tengku looks strong and hearty. Frequently, tengku with above average mental attributes manifest the "aura of the raven's wisdom" and tengku with above average physical attributes manifest the "aura of the raptor's prowess." Both males and females are attracted to both auras and try to manifest both auras if they can. In other words, tengku want to look strong and smart even if they aren't.
It's possible that a tengku that is actually mediocre or worse in physical or mental prowess can have a positive aura misleading or a tengku that is very mentally or physically gifted has a weak misleading aura.

tengku #8 by Zeta Gardner

A tengku with a low Appearance is so unhealthy or derpy looking that he or she stands out from other tengku, in a bad way. Humans and other non-tengku find it offputting and vaguely reminding them of vultures, even if they are not consciously aware of the condition vulturism, they have an instinctive fear of it.
And sadly, more than a few tengku that don't contract vulturism have vaguely buzzard-like appearances. Like with humans, some unlucky tengku are born looking like they were hit with an ugly stick.

Tengku Appearance by the dots

● Poor: Your feathers are patchy, uneven and discolored and you are slightly derpy looking, or your feathers are okay, but you are really derpy looking.
●● Average: At a distance, even tengku having trouble telling you apart from other tengku.
●●● Good: You have a healthy glow or positive aura that attracts admirers from other birdfolk.
●●●● Exceptional: You manifest an aura of wisdom and an aura of power, you magnificent bird you.
●●●●● Outstanding: Your stunning visage of wisdom and power can make other tengku speechless...a rare thing among such a talkative race.

"All tengku look alike!"

Tengku have very little sexual dimorphism, very muted elemental ethnicity traits, and don't vary a lot in height and weight. They all have corvid facial features and black feathers.
Tengku often have a special trait "All tengku look alike" that is Merit or a Flaw, or nothing at all depending on what your base Appearance is.
Appearance 1: 3 point Merit
Appearance 2: nothing
Appearance 3: 2 point Flaw
Appearance 4: 4 point Flaw
Appearance 5: 6 point Flaw.
What this means, is regardless of your tengku's character appearance to other tengku, humans, demihumans and the most non-tengku treat you as if you are appearance 2, because "all tengku look alike".

Now, what about tengku who don't have this trait?

A tengku with a high appearance that carries over to non-tengku carries himself or herself with confidence. Non-tengku sense this confidence and respect it.

A tengku's "appearance" with non-tengku is often auditory, not visual. All tengku are excellent mimics, but in most cases, the tengku looks or sounds just a little fake or rehearsed when mimicking someone or something.
A tengku with a high Appearance that translates to non-tengku can take on pleasing voices to mammalian listeners with more subtlety and grace, literally conveying what they want to hear. They are practiced at instinctively picking either a commanding or a disarming voice when meeting someone new, but without being too obvious about it so as to make a good first impression.
A tengku with a low Appearance that translates to non-tengku often squawks involuntarily while talking or accidentally takes on unwanted mildly unpleasant pitches.