How about Yamada Akihiro? Their style has become very distinct over time.

I've been looking forward to answering this one but I had to wait until I had access to a computer again.

You're kind of right anon, but semantically: Yamada Akihiro's artwork has ALWAYS been very distinct. I'd argue that Akihiro has the most unique artwork of any FEH artist in the game. He's an old-school artist, and I mean that absolutely positively. It feels to me like he has more... I don't know if integrity is the word, but he approaches FEH art with a much higher standard than I've seen from any other FEH artist (not to insult the other FEH artists who do great art). He's only drawn seven characters, but each character is very visually different; he's absolutely skilled in drawing young, old, male, and female characters as seen with haggard old Bantu to fair-faced Mila. Most of the fanbase is really put-off by his style, sadly, but I honestly love it. Akihiro's the only artist who has drawn completely individual art for each phase of a FEH character; none of his characters' portraits are the same to each other, and I find that incredible. His details on characters like clothing, scales, armor, etc, is balls to the wall insane and again, his coloring style is like nothing else in the game.

However, there is a problem with a lot of his art that gets a little distracting sometimes. His anatomy is... funky.

You can see the most egregious examples with Ogma's arms:

Mila's hands

And Gatekeeper's legs:

Again, this is probably the only real flaw in Akihiro's work because in every other field he absolutely destroys it. But it is quite glaringly noticeable. I know that a rule of drawing is that anatomy doesn't have to be absolute if you're trying to pursue dynamic posing or personality shown by a character's body physique. But yeah.

ANYWAYS, Akihiro is very much a 9.99999999/10 artist. I'm incredibly glad they chose him to draw Gatekeeper as he really seemed to have fun with it and gave Gatekeeper such fun artwork. I'd argue we need to see EVEN MORE characters drawn by Akihiro.