.41
The "Police" round consisted of a plain-base 210 grain LSWC loaded to an advertised 970 fps. Winchester and Remington loaded it. Chronographing a half-dozen different lots didn't bear out the advertised velocity claims, averaging about 900-920 through my Model 58...which the round was intended for...and pretty much the same in two 4-inch Model 57s. One lot of Remington in particular stood out, and was eliminated from the overall averages. 10-round average for that lot was around 850. Still not something I'd want to be in the way of, considering that brutal flat nose.
Felt recoil in the Model 58 with its small Magna stocks was comparable to 158-grain .357 Magnum fired in a 4-inch Model 13 with the Magna stocks, if a bit less sharp. Nothing exactly punishing, but it would get your attention.
For a handloader, a cast 210-215 grain bullet with 7.5 grains of Unique nearly duplicates the police load's advertised velocity, producing about 950 fps in my Model 58. Bumping up to an even 8 grains pushes it to over a thousand.
As for me, I very much like the .41 Magnum. I found that I didn't really have a need for a .44 Magnum, and no longer own one. I used a 4.62-inch Blackhawk and a 4-inch Model 57 for hog hunting. A 230-grain hard cast bullet, driven to 1250 fps would shoot through a big, mean pig lengthwise at the distances that I hunted, and usually anchored'em where they were hit. Given that, I can't see how a 250-280 grain .44 caliber bullet at a hundred fps faster could have done any better.
For the IMO part...loaded with a SWC...it's just a good-looking cartridge, proportionally. I consider it just about as close to a perfect revolver cartridge as one can get, balancing adequate power, recoil, range, and trajectory. Power-wise, it can be loaded up to within 5% of the .44 Magnum with standard bullet weights...210 and 240 respectively...and only cedes ground when the bullets get into heavyweight territory. If ever a cartridge and revolver were meant to be together, it's the .41 and the 4.62-inch Blackhawk. It just don't git no better than that.