Honestly I am quite curious to know this myself, I don't know fully well why but I have a few guesses.

Ooh, would love to hear them!

Well my first guess would be is that people don't want to lose their ability to pick up things with their hands. Like they want the animal features without any of the draw backs, and still be able to live a humanish like lifestyle. Plus being to walk on two legs.

Feral is a bit more complicated, some people go this path because they fully believe that being a wild animal is much better than a human lifestyle. You could live in a forest without any anxieties, though that mindset does make it so you don't decide on who you have sex with. Now there is also the option of being someones pet instead, and have someone take care of you. This is usually the more top choice, plus being able to walk on four legs sounds more appealing plus natural vs standing on two legs. You can still have humanish intelligence if you wish though.

Than there is half-anthro, where you are basically feral/walk on four paws but can still pick up things among others. As well as having human like intelligence.

These are just guesses, but also from things I noticed.

Hmmm... I know folks with feral sonas who still think on the level of humans, actually, including mine. A big reason, I think, is being able to experience things from an animal perspective (senses, instincts, various abiliites and/or body parts humans don't have) but with human-level self-awareness so you can have fun with it.

I guess it does depend on the extent to which you are attached to your human-ish lifestyle. I figure in the case of my fursona (feral) there is less incentive to care about whether or not you have thumbs and so on because she has magic and doesn't feel the same drive to make and use tools as a result in most cases.

Tbh it would be cool to write an anthro fic to explore the kinds of things Zootopia got into, among other stuff. But I'm probably going to wind up going ahead with Tarim's story instead, where the closest thing we get to anthros are the half-animal children of weres....

Makes sense, also I'm still excited to eventually read your Tarim story as I'm sure it will be very interesting. ^^ But yeah there are so many reasons people choose there sonas, so it's kind of hard to predict it down to one theory. Glad to hear yours though.