Positives:
1. This is really cute! I know you had a bit of a rough start but you managed to iron out all of the major gropes with Sonic's design. It's a solid first model.
2. The running animation makes me feel like Sonic is actually going really fast. It probably wasn't intentional but it's definitely a plus.
3. It's pretty low-poly so it won't kill my framerate as much as other models do on large maps.
4. Holy cheese you actually included elbow joints this time :D
Things to improve:
1. The elbow joints are still pretty stiff in the walking animation. If you study the way Sonic walks in SRB2 and a lot of other games, classic or modern, you can see the elbows move fluidly between a bent and extended state.
https://gfycat.com/YoungOrangeCygnet
If you find that you can't do that very easily, I think a constantly bent state is better than a constantly near-extended state.
2. Face textures could use a bit of symmetry. This isn't a huge deal since we hardly ever see the face in normal gameplay (except in multiplayer gametypes) and users can edit the textures themselves pretty easily if they want, but still.
3. Why is the jump/spin animation so big? It fits the size of the thoktrail which is a cool idea, but it's so much larger than Sonic himself, so it's illogical. Optimally you should make a jump animation similar to the Tails model you made, but if you don't want to then at least decrease the size of Sonic's current sphere.
That's about all I have to say! :)