I prefer R3 tires. Similar to how an all-terrain is better on a pickup truck than a mud-terrain, likewise an R3 tire is better than an R1 or R4 in snow.
Having said that, due to market conditions and supply, I had to take a new tractor with R4 tires on it. We had a well publicized ice storm in mid-February, followed by two back to back sleet and snow storms on top of that, all in 7 days time. I plow snow on a 400' long uneven paved farm entrance with a grade that's probably almost 10%. I went into the job afraid that the R4 tires would slide and try to kill me. I was shocked to find that the R4 tires did a GREAT job on compacted snow and ice. I had absolutely no issues pushing or pulling snow on the hillside, even at temperatures in the 10F range. Color me surprised, but HAPPY!