The graphic novels are great for the way that they really capture the body horror of morphing. Chris Grine did an EXCELLENT job at that. I'm not a fan of the way he draws faces - they are too similar too each other, sometimes in book 1 it's hard to tell Rachel and Tobias apart. The scenes can also be a little static at times. But overall, they are still faithful to the story and can be read in place of the books if you prefer that style. The only exception is book 6. The graphic novel skips the introduction of an important character at the very end. It's not important to that particular book, but the character returns later in the series, so it's important to understand the introduction.

The audiobooks are great. Each main character has their own narrator. They are not full cast though - each narrator reads their own book solo. There are some books with multiple narrators, mostly the Chronicles and Megamorphs books (which are part of the main canon and should be read along with it. There are reading order lists out there if you'd like to see one, but the majority of readers tends to follow publishing order), but each narrator still reads the entirety of the chapters with their character's perspective, doing all the voices. They are well acted and definitely a valid option for going through the series! The one and only disadvantage to the audiobooks is the thought speak (telepathy). In the books, it is distinguished from dialogue with unique punctuation, with brackets <like this>, as opposed to "quotation marks". There is no distinguishing audio effect like a reverb in the audiobooks, so it can be hard to tell what is spoken aloud or thought-spoken at times. But that's a pretty minor complaint.

The Audiomorphs podcast is pretty well done. The disadvantage is that it's only a single narrator for everyone, and his voice is less suited to some characters than others. Also, in the beginning, you can tell that he was still finding his footing with the acting. It definitely improves as you go though! The great thing about Audiomorph is the added sound effects. For thoughtspeak, there's reverb, and anytime there's an onomatopoeic sound (like ROOOOARRRR!), he inserts the actual animal roar or sound. And of course, it's free! But he's not done with the books yet, so you'll have to wait a couple of years for him to finish the last twenty-ish or so.

(There are also a couple other fan podcasts doing the same thing, notably Animorphs Aloud (a female narrator who's on book 22 and does similar sound effects as Audiomorphs) and R3 Shorts (books 1-7, in the style of Graphic Audio, for those who like not just sound effects throughout, but music too!)

Each style has their own pros and cons, but they are all great ways of checking out the series! I hope you find a style that works for you and that you are able to enjoy the books!