My opinion:
Cutie mark chronicles- Call me crazy, but I actually like this one more. Whenever I see him, he looks very cutesy, and friendly. It fits better with the baby dragon we all know and love. However, I do think that he looks too big, dinosaur-like to really look like a dragon.
Secret of my Excess- This design is really awesome. Whenever I see it, this is what a dragon should look like. Tall, muscular, and sleek. Though, of course since this is a more evil looking version of him, it doesn’t really fit what I’d imagine he’d look like if he was a adult (although this is greed-growth, so it’s suppose to make him look evil…)
I will also give thanks to QueenCold, for the source to help me with the Secret of my excess form.
http://images.wikia.com/mlp/images/e/eb/Infant_Spike_s01e23.png
http://images.wikia.com/mlp/images/5/56/Spike_dazed_S1E01.png
http://images.wikia.com/mlp/images/1/1c/Spike_with_Twilight%27s_bag_EG.png
Notice how in the third one, he is darker and a lil’ more robust?
Dragons do physically mature from time. Look at how Spike looked when he was first hatched, then look at him at the start of season 1, then look at him at the end of season 3.
For a moment he’s in a recognizable version of the CMC form. Really.
I think that CMC (Cutie Mark Chronicles) version may be a more accurate variation. Yes, he’s a bit dinosour-like, but he comes across as big and strong just the same. I imagine land-based dragons to be like that: what they lack in flight they make up with sheer strength. Thus his thick legs not only make him rounded and better-fitting to his personality, they also makes some sense.
Though, I imagine that a more “accurate” idea of what Spike would look as an adult might be a bit of a mix of the two: starting with CMC-Spike, add longer neck and legs, with a slightly sharper maw.
as for Greed Spike has the higher Agi and Crit rate.
set aside the MMO nerdiness… I like Good Spike more. that IS the Spike we knew and loved, and I hope he grows up to that point.
Also, add wings.
Also, I don’t like Greed Spike’s… err… spikes.
In Cutie Mark Chronicles Twilight’s magic didn’t mature Spike, but just grew him. That, or she turned him into something else, like a dino. Who knows, she did turn her parents into plants after all. Noone said she turned him into an adult dragon, even if he did sorta look like one.
In Secret of My Excess Spike’s growth was also unnatural, but he did mature. It happened too fast, though. He had too little time to adjust before growing into a more mature state.
The more he grew, the greedier he got, the less time he had to adjust. This is why he looked fairly normal in his earlier stages, but got some really jagged features in his later stages.
His natural adult form probably looks like his adult greed form, but less monstrous.
Also it’s amusing that neither have wings