You're probably too late to the party to be effective with either. Of course, I guess we all know 2,4-D kills broadleaf weeds and has little effect on grasses. Rye, wheat, oats are all grasses. You can hurt them with 2,4-d, but not if mix correctly.
Amines are heavy while esters tend to vaporize more readily. I know the label says lo-v -- or low volatility, but it is still more volatile than the amine. So, if you need it to say in place (more/better), use amine. That's the bad side of lo-v. It has a good side. Because of its chemical structure - which makes it more ready to take flight, it more easily breaks down the waxy leaf surface of the target plants so that absorption is more and better. The result might (might) be a better weed control/kill.