So I finally made some dino examples in single player of what I'm looking for in an Allo and Spino... after a bit of messing around that lead into "fatal errors" and eventually leading to me having to delete my save file to even log in to The Island anymore. Not sure why... I was just running around on my Thyla with an Arcaeopteryx in my arms above my head, having fun with the glide ability. Oh god I need one on official. It's so fun, and they're so cute.
Anywho, so these are actual wild colors. I used the Wiki pages to look at what colors they could have in each area and found what I liked best out of those.

First: Black, Black, Light Gray
Second: Black, Light Gray, Black
Third: Black, Light Orange, Light Gray (This is the boy I wanted to tame, but took some convincing and was gone by the time I returned with my Quetz, Wolf, and Narqs)
These are both mutated colors, I believe. I know I've seen them in game. I think... I know Rubble has a blue one and Pillars has one as well that's a different shade than Rubble's.

These are my "Dream Allos"
This is what I'm looking for in a Spino, although the all black one Nef got is also something I would like.

Black body, Light Blue belly, Light Blue sail, and the sail top was.. purple? Blue? I forget.. or maybe I made it black. Honestly any of those three would be fine.
I actually found a boy like this a while ago, right above Green Obi. I posted the story about it back then. He was alive for hours and then when I finally came back to tame him he died within the couple minutes it took me to find a safe area to knock him out.
I've been meaning to post pictures of my house progress, I'll try to do that later. I took some but then worked on it so they were outdated.