Now I'll try to break down these different animals in regards to why I have them ranked as I do, though that's not something I can even remotely explain in full.
Top of the list, Mongoose: this has been the one I've considered and been drawn to consistently the longest of the ones listed here. And although meerkats are a type of mongoose, I feel pretty sure meerkat is not my theriotype, but there are notable similarities for the fact it is a mongoose (and thus being able to watch meerkats on TV, like Animal Planet, helps in that regard), yet I can't find myself being similar enough to them therianthropically to use them as a way to verify mongoose as my theriotype. As far as I've found, if it is mongoose then it's something more akin to a yellow mongoose or a similar-in-body but possibly more solitary type of mongoose (though here's where I run into the problem of not finding photos, media, and much of any, if any, info on most of those, even though I'm not trying to narrow down passed mongoose, it could possibly help a lot to find more media and info on those others that may fit well).
When I see photos or video of mongooses doing their distinct standing position, it reminds me so much of my theriotype concept in how the body is structured and positioned when standing, and that they stand digitigrade--something reflective of how my body "feels" (in part phantom sensations and in part mental understanding) when I stand digitigrade (which I'm often prone to do; I know that toe-walking is common among therians, and probably just a digitigrade standing position as well, but there are specific and more distinct aspects, sensations, and mental thoughts/feelings to it when I do it). Their forelegs are also more similar to the concept I have of my theriotype's body, they aren't paws, per se (like canine or feline paws), and they aren't plantigrade (though I'm not completely sure if my theriotype's are plantigrade or not, but the digitigrade forelegs fit better it seems so far). Mongooses are mustelid-like, but don't have the extra long bodies and short legs of mustelids (which I have consistently felt those attributes didn't apply properly), and they are also cat-like and canine-like in various ways--they're like a strange mixture of cat, canine, mustelid, and ground squirrel, which fits well with all the attributes I have repeatedly observed and noticed as parts of my theriotype's concept. My pull is the strongest to mongooses, however I'm not yet comfortable calling it confirmed because I still have some unresolved attributes of that concept that I feel I need to rule out from being of other types of animals (mainly the other ones in the list).
Ground Squirrel: this is a kind of interesting one that I wasn't expecting to make it this far, but it initially came to my attention as a possibility sometime this past summer, most notably brought about through prairie dogs. I watched most of a documentary on prairie dogs as well as got to see them at a zoo during summer this year and I noticed how much they reminded me of and seemed similar to meerkats (which I've also watched on TV). They have similar behaviors, mannerisms and poses, and some similarities in social structure, and some aspects of their bodies fit with my body concept for my third theriotype, and after doing some more research I noticed that there are numerous types of ground squirrel that hold these similarities as prairie dogs do (and some may hold more similarities to my concept). I'm also considering them because aspects of tree squirrels seem to fit well with numerous aspects of my theriotype concept, but I have ground squirrels a step above tree squirrels because of the seeming lack of my theriotype being primarily arboreal, among a few other things.
And yet, I don't feel ground squirrel resonates with the number and quality/extent of my theriotype's attributes as mongooses do, but I'm trying to lay to rest whatever confusion I've been having that's making it difficult for me to decide most particularly between ground squirrel and mongoose. I'd also like to note that when I think of the mentality for a ground squirrel (or most small rodents), the mentality doesn't align nearly as well for me as mongoose does (especially with mongooses being prey-minded (some of them at least) as well as avid predators and carnivorous), but I could also very likely be misconceiving that mentality because not all small rodents, including ground squirrels, carry the mentality I perceive them to have (prairie dogs are probably a good example, though they won't fit the predatory aspect--yet I'm unsure of the extent, if any, of the predatory part of my theriotype). On another hand, I wonder if the reason for perceiving small rodents that way and mongooses the way I do is some indication of what my mentality in regards to my third 'type is--in that if it isn't rodent, then to avoid or reduce such confusion I subconsciously I don't conceive their mentality as the same or similar enough to my theriotype's.
Tree Squirrel: it holds some of the similarities in behavior, mannerisms, and body structure that fit numerous aspects of my concept, many are similarities that are held by ground squirrels, some more accurately portrayed through tree squirrels and some more accurately through the ground types, while as with ground squirrels they come up short in some significant areas that mongoose so far (above any other animal, that is) fits.
Marten: actually, up until recently I was still about to completely exclude mustelids from my top possibilities, but after looking up a bunch of photos and finding some videos of them, I reconsidered them. They are the most 'mongoose'-like of the mustelids I've come across, and an interesting blend between mongoose, cat, and canine (not much in the rodent aspects though). The ferret-like and weasel-like mustelids just wouldn't fit, particularly because of body structure (and the impact that has on their mannerisms, movement, and behavior), and badgers, fishers, skunks, and wolverines also came up too short to be considered this high on the possibilities. I have issue with getting aspects of marten to fit though because of the pine marten's arboreal nature--and I'm having trouble finding photos, info, and video on the other types of martens, as well as it being plantigrade, in which rodents are plantigrade as well, but the squirrel-like feet still fit better than the bear-like feet of martens, and their forelimb mannerisms are lacking in being as reflective of my theriotype concept (one that's so far best represented through mongooses and squirrel-like rodents).
Other Rodent?: I'm not even sure this category should be on here, but I suppose it's meant as the next highest possibility with it maybe being some other type of rodent (not tree or ground squirrel) that I just haven't looked into enough, even picture-wise yet. I'm doubting this one currently, but it's higher than the things that aren't on this list.
So that lays out the basics of where I'm at now, and it gives you all a better idea of what point I'm at regarding this considering I've been immensely vague on this subject this year. But for a bit of a change in direction, I'll mention a little about my progress pertaining to my possible avian theriotype. Do I even know it's a theriotype yet? No, I don't, I'm still slowly, and of course rather passively in manner, trying to figure that out, though my mind keeps telling me it is a theriotype, just the most fragmented of [what would be] my four 'types. Recently while I was looking through my animal encyclopedia/reference book for possibilities for my mammalian, third 'type, I looked through the avian section to see if I could determine any leads on what type of bird that avian aspect is. The possibilities I came up with are cranes (no idea what type), secretary birds, storks, seriemas, and maybe bustards (haven't looked into them yet, but they were listed near seriemas and had some notable similarities that possibly fit with how I perceive my avian aspect). If not any of those, then I haven't come across the basic or specific type of bird it is or it's something ancient and extinct (which I'll wait quite awhile before journeying down that road--I want to exclude modern (particularly still living/extant) avians first before getting into considering it strongly as earlier avian, proto-avian, or avian-like dinosaur).