There are too many powders for the .243 to list all of them. First, you need to decide what bullet weight you prefer. Heavy bullets need slower burn powders; light bullets fast burning powders. Varget is one of the very best for all applications.
Standard 243...H4350 with Sierra 85gr and AA3100 for the 95gr Bal-Tip. Sako firearm BR-2 primers.
RL-19 in my 243AI Lapua brass BR-2 primers and 70gr Hammonds down a Douglas barrel 1-14. 1-9 Pac-Nor barrel 243AI 105gr Hornandy A-max over N-165.
varget and I-4064 for the lighter 85 and under, h/i-4350 for the heavier. have not tried re17,19, or 22 but have had good results in other calibers with them. there is some more info on 6mm.br for the .243, and re-17
I run IMR-4350 with 100 grain Nosler Partitions, the load I use being three grains over book max with no pressure signs. Groups out of my old Savage do under an inch for three shots @100, do just over two inches @300. This load is like a death ray on our rather smallish (under 200#) deer, kill as well as my 7mm R Mag out to 325 yards
If you have a standard 10 twist barrel, you then have to settle on a bullet weight. depending on your barrel length you may want to look at a little slower burning powder. However, if you have a standard 22-24 inch barrel, two good all around powders are H414 or Varget. Both cover most of the bases pretty good and there is plenty of load data out there. Once you find something that works well for ya, stock up! Good luck!