A few weeks ago, I gathered all of my own .243 data, and data I've collected from other sources. Then, I plugged it (nearly 600 loads with 33 different powders) into a spreadsheet with a formula that spits out a numerical rating (0-50) for each powder, based on weighted aggregate values for consistency and efficiency.
Top 5 powders, in order of awesomeness and versatility in .243 Winchester - 80 to 107 gr bullet, 24-26" barrel (numerical rating in parenthesis):
IMR 4064 (44)
Viht N140 (30)
Viht N160 (27)
Reloader 15 (16)
Even though IMR4064 has been edging its way up as my go-to powder choice for most .243 loads, it was surprising to see it surpass Vihtavuori powders in the list - particularly with so few of my own loads in the data set.
One of the reasons those ratings have such a spread between them, is the way the weighted values work in the formula. It was designed to show a wide enough spread that a distinction between powders was magnified and easy to see.
Most interesting to me, was that the formula didn't like IMR3031, at all. For decades, it was considered to be "the" powder for .243 Winchester. But, I don't know anyone that has had much luck with it in the last 10 years, or so. The formula agreed, by spitting out a rating of two -- the same as Big Game, BL-C(2), Reloader 19, and H4350. (Though, IMR4350 made a moderately better showing, with a rating of 7.)
Obviously, those ratings are for attributes that are important to me, but I tried to be as fair as possible. All I was really trying to do, was see if my own preferences for powder could be backed up by a larger data set.
"Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."