The newer one is definitely better, except that you seem to have made his arms shorter for some reason. They were fine, or maybe at most a pixel too long.
If you're going for a beefy look for him, maybe give his legs more definition too? He looks rather strange having noodle legs with such a body.
People's clothing rarely rests perfectly straight on the body. It's unlikely that we'd see Finn's shirt make a perfectly straight horizontal line where it meets his shorts, it would probably curve downward, or rest a little wideways. There would probably be some folds in it, too. You've already got a nice, natural-looking curve of resting fabric with his hood, his shirt should be somewhat similar.
Similarly, we very rarely see people (or any large object) perfectly head-on, we'll usually see some part of them from above, such as their thighs and feet. This means those parts will have a slight curve to them. Even in sideview games where doing actual perspective would break a lot of the art, artists often incorporate subtle perspective stuff like curved short hems and curved socks because it looks more natural.
A lot of your vertical edges have 2-3px "steps" inward, which makes the piece look lower-resolution than it is and very jagged. Smooth, gentle curves should only step by 1px. Larger steps are good for sharp corners, overlapping objects, etc. In case I didn't explain it well, here I've highlighted the stuff I mean:
Nitpick: His backpack looks like it's about to fall off, the straps don't look like they're attached to it at the top. Straps don't have to run perpendicular to the shoulders, and IRL they rarely do. Try making them run more towards the middle of his back. This means they'd be vertical or almost vertical lines in the image.
I don't think you need the lighter parts towards the tops of the straps, unless that's part of the design in the show.