Basically, I like various types of character design.
I'm a sucker for costume design like cool armor designs such as Saber's:
A practical armor that still allows her to look agile yet powerful(also thanks to the non-visible-here shoulder pads) alongside a beautiful combat skirt to give an image of an elegant and strong fighter.
The color palette is also important to note: the silver armor plates just go so well with the blue dress and that matches perfectly with her blonde hair and green eyes. Giving her a calming aura with her bright colors.
Then there are those that are simply fancy, those that wear coats, capes and the such, for this, I have one main example:
First is Akutagawa from Bungou Stray Dogs. Really, I could use anyone from this manga because the designs are just so good, but I'll try to stay focused on him for now.
Coats like this one are simply badass, they look cool as **** and make a character intimidating, especially if a ****ing demon pops out of it. With his coat seemingly enveloping his slim stature with a vampire-like collar at his neck tells you what you need to know about him. The black/white palette also works perfectly since both parts of his hair have the same shade as his clothes.
Though I also think it's important to show another example, in this case, pst-Rideout Raid arc Shigaraki
Because he just looks so cool with that coat. Also, the hand serves as a mask, I guess, this is going to be relevant soon.
Then there are those who aren't human, not even organic. I'm talking about robots, because I love me some robotic designs.
Grievkus in Episode III would never have won me over with just his character. Hey, he even has the cape thing going on! The skull-like head isn't even the best thing, he as a whole looks like a robotic skeleton and that's just simply way too cool.
But speaking of robotic designs, there's one that wins over without a doubt.
The Mechon designs from XC are just great, but Metal Face is easily the best: from his weird proportions compared to a human, to the sharp and long claws and the gold and black palette with only his face to contrast with the rest of it. Metal Face screams intimidating, he looks unusual, with or without the context of XC: with it, he has a face, something Mechon aren't supposed to have which gives a weird feeking since this killing machine has a "face" to it, in both sense, the one that it's distinguishable from the others and that it can look onto your very soul with its eyes as it cuts you up like a hot knife through butter; without it, well, he's not a standard robot or mecha or whatever, his limbs are way bigger than anything else he has and, for some reason, a tiny headed scissor-hands man with giant arms and legs just leave you unnerved.
One thing I also like is not being able to tell the character's expression, which I guess plays into my love for robots. It can be a mask, a helmet anything, really, I just like having to read them based on body language and context alone.
Be it the classic Darth Vader
Or his clones like the Black Knight
Darth Vader Clone is the best trope in existence fight me
Or the more literal uses of a mask like Tobi
Sometimes the mask just looks good really
Sometimes it's not as mask or a helmet, it's just straight up their head but they can't physically emote with it
I don't know, something about them is just so endearing to me. Shigaraki also fits here thanks to the hand he effectivelly wears as a mask, though I'd like to add that his removal of the mask is th only one that's used to accentuate his creepiness.
Also, for those that mentioned liking suits I present you exhibit A
Finally, I want to end with "how to not design a character"
I don't think anyone wants to hear me go on a rant about Pyra or Camilla, we all hate blatant fanservice, let's jump to the real issue here: bad costume and color combination.
Want a good/bad example of this? Look no further than Akame ga Kill
The first problem is that most of the costumes have nothing to them: Leone just has a black top, Tatsumi wesrs a sweater, Najenda's outfit and eyepatch as bland as you can get, Incursio is just a bland white armor that looks more like a scaled down mecha, etc.
Then there's the costume choices, like Akame having what seems to be a school uniform(her sister outright wears a sailor fuku), Tatsumi with his out of place sweater again, whatever the hell Sheele's wearing(the one with the glasses), etc. They all just clash because they're from vastly different periods in something that's supposed to be(mostly) a medieval setting.
And THEN there's the issue with their color palette, most of them have two or three different shades of the same color, or have colors that don't match at all, and this is just the main cast so trust me when I say it gets worse.
WHY THE **** IS SHE WEARING HEADPHONES
THERE DOESN'T EXIST ANYTHING IN THEIR SETTING TO USE THEM ON
WHO DESIGNED THIS ****