The analogs are much more convenient to use. The short acting ones take effect much quicker, for a shorter period, and more consistently. The long acting ones (generally considered ~24 hours, but not really) are much more level in their effect (less spikes in it's efficiency).
Instead of figuring out what you're going to eat, taking insulin for that, and waiting 30-60 minutes before you can eat; you can take them pretty much right as you eat.
Instead of your blood sugar rising or dropping "randomly" over the course of the day, it tends to stay more consistent (though your body may decide otherwise).
That being said, with enough testing (or a CGM, but that can be costly too), the older insulins work just fine; they're just annoying to use. You see your blood sugar going up, you exercise some; you see it going down, you drink some OJ. I tend to have to do the same with the newer insulins AND a CGM; just a lot less so.
