I'm not an artist, but I've seen a lot of art.
My favorite is the first one, the second one had a bit less proportions and the last one has gigantic feet.
The first one has a lot of potential and very expressive eyes, even with the minimalist art style.
The second one has an interesting design balancing the ears with the suit, beastly and formal at the same time.
The third one is the weakest of the trio, the face doesn't have the same feel as the first one and the body looks kinda outta of whack.
I've been practicing a bit recently, mostly to be able to draw storyboards for work and I think you could use a bit more practice on the basics, trying to keep your art more consistent and channel more of the energy of the first one, rather than the third.