hum... i kinda like the earlier one better.
And i hear you about giving artists leeway on some aspects. Hard to be a pure black fox and not have some XD

I had made a mistake with those pics, but it's fixed now.

Although, what did you consider to be better about the earlier pic, which was the incorrect, to the more recent. They're both the same colors but was it just the size or something?

I think the ref sheet had more detail. Like it had the red outer, red inner like most but it also had that touch of brown at the center. It might have been the size, sure. but chances are it was more the artists style

on the current 2, i like the earlier one. the darker yellow is less contrast to the red and i think it meshes well. The eye size in the early one matches the face more in my opinion

Now see, it's funny that you say that darker yellow looks better cause the first pic with his face, it was almost orange https://www.furaffinity.net/view/41937017/ and yep that's the first pic of Michael's face. I had plenty with him before but it was usually just his hands, hips, or dick 😅

That is funny XD. Looking at this pic gives me a thought. while normal/peaceful his eyes are that dark shade of yellow in the first image. then, while going more wild, they glow a bright yellow.

His eye color looks the same to me, just looks like his iris used to be bigger

Whoops, I posted the wrong pic, fixed it now 😅 It's definitely different though, the iris used to be red with yellow sclera, now it's usually reversed with yellow iris and red sclera

Honestly the choice is up to you
The hair stuff can be explained easily as either she is getting older and her hair is just naturally getting lighter or have it as a seasonal thing, if you want you can make is so black is the regular color and light brown is the Alt to allow you and the artist have variety
Same with the eyes, allowing the opportunity for variety, a friend of mine has one of their characters that has that setup on the character's reference

Yeah, and that's how I've generally let it be in the past. That it changed depending on the lighting, which makes sense. My own hair color tends to shift depending on how long it is, and therefore how much sun it gets. Just wondering if I should be consistent with it. I think my idea is that it should be darker compared to the fur on her forelimbs. I don't want them to match.

As for the eyes. Well I messed up and posted the wrong pic for the early design. So take a second look at that. Really, I'm just not sure which looks better and should I just go back to my original idea. Of course I used to also have the idea that he'd always look a little evil, but I definitely abandoned that idea.

I'm kinda leaning more towards the yellow, because dark red kinda merges with the pupils. Maybe a brighter red.

But it's ultimately up to what feels good to you. c: Someone once told, if you can't make up your mind, flip a coin. If you like the result, go with it. If you don't like the result... it means you actually prefer the other.

So like:
heads=yellow
tails=red
You flip, get tails, and go "aw shucks, I was hoping it would be heads;" that means you prefer yellow, so use yellow.