Rather jaded on this question haha! I love APSC, 100%. You get more reach with a lens of MUCH smaller size and now-a-days they are pretty much the same quality. The full frame + massive lens is the preferred set up of people on photo tours in a van, who wont walk more than 50 feet with their 15-20 lbs lens and kit and generally shoot middling pictures, almost entirely of birds. If you're a casual shooter, don't fall for the trap of wanting to look like the pro (who also has a team to haul gear, I know I've hauled the gear for a lot of shoots or guiding haha!).

In short, youre going to get better wildlife shots if you can actually hike and be speedy with movement and the camera. Shooting a lot is what gets good wildlife pics, not the camera. Only other time I would use the full frame huge kit + rocket laucher lens is a pintil mount / shooting out of the car in Africa, or sitting in a blind with a tripod for a very specific animal. Yellowstone wolf spotters might be the one other exception in the US, as most people shoot roadside. However, being able to hike, get to more remote areas and be more likely to always carry your camera is what gets good shots. You get to a eco lodge, youre tired you want to go for a quick hike, grabbing the light APSC with a 300mm (i.e. 450mm) zoom on the shoulder, no tripod, and hopping out the door is where it's at. Hot sweaty, haveing to put a huge camera in and out of a bag is no fun. Also, small kit is less obvious and makes you a much smaller target for crime internationally.

Finally, I find the obsession with wildlife people talking about high FPS for wildlife is purely bird people (who also compare lens sizes not quality of pics) and try to shoot birds on the wing. Which is hard no matter what. If you dont shoot actively flying birds or sprinting lions all day you, the hyper fast fps is just marketing. You will quickly dial it back as suddenly your post processing has increased in time by 10x and you have to sort through literally hundreds of nearly identical pics, 15-20 shoots per touch of the button to find the best one? Gross, post processing becomes a big chore and I end up shooting less. But.... people on photo tours love to show off the BRRRRRRR of their camera machine gunning away to other people while shooting a duck.... quietly sitting in a pond.