The product you attached here looks fine, but instead of looking at the ratio of analysis nutrients, I would look at what your soil test values and what you've used for fertilizer earlier this year. What does your soil test tell you about P and K? If P and K aren't needed, you're just wasting money (and possibly polluting the environment) by applying them. You won't get a greener looking lawn by applying more P or K than what's needed.
Also consider how much of each nutrient your lawns will need. The application recommendations on the fert bag are based off the N amount. The product you showed applies about 1#N/M according to the directions, which means that the 3-1-2 will apply about 1#N/M, 0.33# P2O5/M, and 0.67# K2O/M, while the 4-1-2 applied at 1# N/M will deliver about 0.25# P2O5/M and 0.5# K2O/M. If your program calls for 1# N/M and you need more P, the 3-1-2 will work out better for you. If you need more K, the 4-1-2 will work out better.
The bottom line is that the analysis doesn't matter. The only thing that matters is how much nutrient do you need and how much do you apply. 3-1-2 vs 4-1-2? If your soil tests have adequate P and/or K, neither of those are your best options.