Boa morphs that don't change?

[WrongPython]

If it's your first boa, I would also try to find one you connect with. Most are pretty chill, but see who speaks to you. Hard without reptile shows now, but at least talk to the breeder and get a sense of temperament and food response. One has nothing to do with the other, but both should be good.

This! In the long run, you'll probably be happier if you chose the boa you best mesh with over the one with the prettiest colors. Pretty colors won't make up for a personality you clash with, especially if you're just looking for a pet! That said, you should be happy with the color of the boa you buy, so try to hold out until you can find a boa that has both the personality and the colors you want.

Onward to grey boas: the Colombian anery gene (ie. the one you're probably dealing with when someone says "anery") does brown out with age, unfortunately. If I understand things correctly, the black-eyed anery and Nicaraguan anery genes do stay grey throughout their lives, so those may be worth a look. You'll want to double-check with a breeder of those genes on that, though. There are also a couple locality boas that are naturally grey. Crawl Cay and Caulkers Cay are normally grey, and there are anery lineages of Nicaraguan, Paraguanera Peninsula, and Sonoran boas as well (though the latter two are harder to come by). Anery and hypermel longicauda boas are worth a look as well, though they're admittedly more dark than grey.

As far as other morphs go: jungle, from what I understand, is kind of a color-enhancing gene. The older jungles I've seen tend to be pretty vibrant, especially when there are additional genes like hypo at play. Leopard may also be another morph worth looking into. It tends to introduce darkness and reds on top of the complex leopard pattern. Some leopards even darken out like IMGs as they age -- it's believed that there's a Sonoran IMG linked to the leopard gene, so it may actually be IMG after all!

if you'd like to scout out what morphs look like as they age, try ordering the boas available on MorphMarket by "oldest birth." Typically there's a few older boas posted there, so you can get a feeling of what some morph combos look like as adults. There are also normally some older boas posted on FaunaClassifieds that you can check out as well. Checking out breeders' Facebook pages may also help, and a good breeder should be willing to send you photos of the parents of a boa you're interested in if you ask.

Good luck! If you're looking for breeders to check out, I can recommend Vin Russo (Cutting Edge Herp), Allison Theus (Crispysnakes), and Warren Booth (Boa Booth). I have two lovely boas from the first two and am looking to pick up a third boa from the latter (when the next litter of the specific locality morph I'm looking for comes along).