I've been reloading since the early 70s, and am currently set up to load for over 30 different rifle and handgun rounds, ranging from .22 Hornet to .458 Win mag.
I've never had really bad results with any suitable powder, but in some guns, some powder are just mediocre, and others really shine.
IMR 4064 is an old and trusted friend to me, along with many others. Good place to start, and good standby as well. The only down side to the stick type powders is sometimes they don't meter smoothly in the powder measure.
Ball and flake types meter like water, usually.
"Overbore" cases (large capacity vs bore size cases) often turn in their highest velocities with slower powders. Accuracy, of course is dependent on the individual rifle, and its load preferences. The .22-250 and the .243 are on the overbore side of things. You may get a benefit from the slower powders in these cases, you may not. Again, individual rifle preference. I generally use medium rate powders in these calibers (IMR 4064, 4320, WW 748, etc.) and have been getting very acceptable results for decades. IMR 4895 is my go to powder for all the WWII milsurp calibers, and certain Hodgon and Hercules powders are very useful as well. H380 was intended for the .22-250 and the classic load (38gr w/55gr bullet) has been very popular for a long time.
The current situation of on the shelf powder (and everything else) availability truly sucks. Get what you can, try it. When you can find something else, try that. You may find a wonder powder that works really well in everything you have. You may not. Either way, you get to shoot to find out, and that's never a totally bad thing, right?
Good Luck, and if I can be of any help, just ask.