I selected W296/H110, because the question was 'favorite Magnum pistol powder.' In my mind, for full-house Magnum loads... you can't get any better. Yes, you pay for that.... with charge intolerance, having to use Magnum primers, boom and blast... but it delivers. I hardly use it. These days I rarely shoot full-house, jacketed bullets in pistol cartridges.
I have not used 2400 pr IMR4227 since the early 1990’s (2400 was still a Hercules powder). 2400 left too much nburned powder in the chambers and IMR4227 just did not produced the required velocity. Maybe things have changed in the last 20-25 years.
My real favorite 'almost Magnum' powder is IMR4227, followed by 2400. I call it 'almost Magnum' because it won't deliver the performance of W296/H110, but it's pretty darned close, and is easier to manage.
First... 2400. I tried 2400 many years ago, as Chuck mentions... back when it was Hercules... and I was not impressed with the accuracy I got with it, particularly in the .41. I used my one can and left it behind. Then, during the Obama Powder Shortage, I picked up 2 cans of IMR4227... because it was on the shelf. I hated it at first... it acted very much like 2400, with the added 'bonus' of being stinky and dirty... far more dirty than what everyone points to Unique for. I thought... "Gads! I've got 2 pounds of this garbage to get rid of, now???" I was due to drive to WY for a steel shoot, I decided to just load all that IMR4227 up in the .41MAG, shoot it out of my Marlin... and be done with it. I bumped the charge up to an even 20grn, and loaded up about 700 rounds. What I found was... once that case fills up and taps the bottom of the bullet, THEN it works well! I came away from the WY shoot very impressed. Not only did it work well in the Marlin, but I was making 6 for 6 shots at the steel at 500yds... with my 4" S&W! The dirtiness went away... completely in the Marlin, and very nearly so in the 4" Smith. Obviously, the key is case fill and bullet weight, with barrel length a distant 3rd.
ETA: As far as IMR4227 being 'dirty?' Not at full pressure. I shot all 700 of those rounds and more, over the weekend... no cleaning, no brushing, just hammer down, 10-4. No issues with a dirty action, no barrel fouling (and this with hard cast commercial bullets...) and no degradation of accuracy.
Circling back to 2400, friend of mine sold me 3 pounds after the WY trip. I gave it a go in the .41, again, working it up to as much case fill as I could. Like IMR4227, it performed better at nearly full case fill. The accuracy was better than I remembered, but it wasn't as good as IMR4227... so I made the choice to trade off my 2400 for some .45 bullets, and commit to IMR4227. In fact, I just bought another 8# of it last month. I also used 2400 for some reduced .45-70 loads, where it did very well... much better than Unique and other faster pistol powders. In the .45-70, I've moved 100% to IMR4198... so the 2400 was a moot point, anyway.
I played with charge weights... IMR4227 in the .41MAG... with QuickLoad. I understand, more now, how those slow pistol powders work. As case fill rises to 100%, the burn becomes more efficient, and more complete. With a starting load of 18.5grn IMR4227, the QL mark of '95% burnt' doesn't even show up in 20" of Marlin barrel, but once you go to 20grn, it shows 95% burn at about 16" (I'm going off memory, that may not be exact... but it's close.) I suspect 2400 is very similar, although I did not run the numbers. I suspect most load data for W296/H110 is up there, already... hence the inability to download the charge, making the burn unstable. I'm not a chemical engineer, but that's my spin on it.
I've not tried any of the other powders listed in the OP's survey... I haven't found any reason to. I do have a curiosity about AA#9 (...and AA#7) but not enough to go out and try to find a can. Same-same with 300MP (which has been described to me as 'quite blasty') and Lil'Gun. I went through one can of BlueDot, back in the Hercules days... and I was not impressed with it, either. I will admit... I didn't use it right; it needs the same treatment as 2400 and IMR4227... a full case and some pressure to work right. However, Alliant issued a blanket warning against using it in the .41MAG... and I don't normally flout very specific warnings from manufacturers.... so BlueDot is a no-go for me.
oison" and load on.
