Gryphon Books
Summer King Chronicles
(Jess E. Owen)

I started the gryphon category for this series alone, because it's just that good.
On the Silver Isles, tensions have existed for years between the Vanir and Aesir gryphons. The Vanir were a native tribe living in relative harmony with the other animals on the isles, until the Aesir conquerors swooped in from a different continent and took over the tribes. Now, years after Sverin, son of Per, declared himself to be king, whispers in the wind speak of a new ruler, a so-called "Summer King" who will bring peace back to the isles.
Summer King is a series that does several things very well, and foremost among these are its themes about regret and redemption. This is an extremely well-intentioned book series: the kind that wants to believe people can change, and that they can make the world a better place by doing so. It's a series that's concerned with peace and conflict resolution, and the degree of respect to which it gives its characters (with some in particular standing out more than others, but I won't spoil that here) is something to be admired. In this regard, it reminds me of MCA Hogarth's writing.
I believe this series improves with each release, to the point where I can call book 4, By the Silver Wind, one of my absolute favorites books, period. The only criticism I have of it is that it could've used an extra chapter or two to flesh out the ending a bit more. Aside from that, By the Silver Wind had me invested every page. It hit me on an emotional level that's comparable to Golden Treasure, or the best parts of Serpentia, and that's some high praise coming from me. Great pacing, characters, worldbuilding: the whole nine yards.
Summer King has many lovable characters, with the most obvious one being the main gryphon, Rashard (aka Shard). Alongside gryphons, this series includes several other animals such as wolves, eagles, lions, and even dragons. I do wish some of these other animals had been given more time to shine, especially a certain wolf we meet during the first book. But I never felt like this was a major issue. Book 5, The Starward Light and Other Tales, is a collection of 3 short stories that expands on some of the events following the main plot, and I found this to be a welcome addition to the series. I would love to see more short stories like this added in the future, if the author is interested.
Overall, I give Summer King the highest recommendation I can give. It's a fantasy series that's worth reading whether you care about gryphons or not.
Length: 247 pages (Song of the Summer King), 398 pages (Skyfire), 384 pages (A Shard of Sun), 477 pages (By the Silver Wind), 188 pages (The Starward Light and Other Tales).
Dragon Star Saga
(Jess E. Owen)

As expected, the sequel to Summer King Chronicles makes it onto the list too. Instead of focusing on older characters, Dragon Star comes with a largely new cast of gryphons, wolves, and dragons, with the protagonist being a curious blue Aesir named Ren.
This series only has 2 books out so far, but it's looking to be just as good as Summer King ever was. Book 2 in particular has already crushed my soul like the best parts of Summer King did, and this gives me high hopes that the rest of the story is going to deliver as well. The wait for new gryphon books might just drive me crazy, man.
Length: 350 pages (Rise of the Dragon Star), 355 pages (Shadow Sun).
Raven Kin
(Nerine Dorman)

In a world populated mostly by humans, a handful of rarer alchemical species live under their masters' watchful eyes. Silas, a raven gryphon, is one of these alchemical creatures. He cares deeply for his mistress, Anwyn, but when things start to go sideways in the family business, Silas is left wondering what's going to happen to him and the people he cares about.
Raven Kin is a short book, and for the first half, I was worried it wouldn't have much to do with gryphons at all. Despite being written from Silas's PoV, the story is mostly concerned with the lives of humans. During its 2nd half, however, this book picks up the pace and delves deeper into the gryphon's role in this world. Because of this, I definitely liked the 2nd half more than the first. There's some good storytelling here regarding slavery, freedom, and wild instincts, and it can get surprisingly violent at times.
Like with many short books, I found the biggest problem of Raven Kin to be the pacing. It gets rushed in the last few chapters. I also felt that Per, a human character, was unrealistic and sadly got forgotten about by the end. Aside from these problems, I liked this book. It seems that there were once plans to make this a full series (called the Blackfeather Chronicles), but Raven Kin has gone the route of Dragon Prayers; not a word of book 2 has come out since 2015/2016. A shame.
Length: 195 pages.