In .177 and .22, I have had the best luck with Crossman Premiere and JSB, hunting and/or targets.
In FT, we have a 20 ft*lb limit, so most of my work has been at that level, but at times I have sent them much harder.
Serious folks end up with even larger bore designs, but I live far from where I was raised and able to hunt, so I am not ready for all the .25 and up rigs yet.
In FT, the dividing line from where you would call an average difficulty is about 1" at 40 yards in low or no wind. You can do much better with tuned rigs, good optics, and lots of trigger time. More than good enough for head shots on squirrel and rabbit using 20 ft*lb with accurate pellets.
I don't recommend body shots if you are collecting the animal, so it is all about head shots when hunting for the table, for me that is... Nothing wrong with a well placed body shot, but to be well placed it is just as tight as a head shot in my opinion, and then the uncertainty of the lethality comes into play.
Good Hunting in any case!