Recipe difficulty is based on rank, with a few complicating factors:
-Some recipes require certain facilities, and not having the facility increases the difficulty by an unknown amount.
-Some recipes require certain training (or maybe it's better to say "benefit from certain training"?) No training, you'll have a harder time. A lot of the "oh god this is hard" recipes have an associated training. No telling if the effect is the same everywhere.
-We know moon phase has some sort of influence; it might be negative under certain circumstances.
But once you've got two or three crafts past level 10, you can equip abilities that you can activate at random; the right selection of abilities can seriously help out. (I personally recommend Preserve and Fulfillment; between the two of those, I'm doing leves and hitting 100-plus results with fairly mediocre equipment. But other abilities are good too...)
If you're leveling, you SHOULD care about quality. You get a little more exp for higher-quality synths (though, perversely, I've gotten less for an HQ synth; not that I was complaining!) I mean, I suppose if you were grinding out some loser recipe and you were just going to throw the results away at the end, you might just hammer standard, but isn't it early days for that kind of grinding?