Outlaw Forest also drops herbs - the place is fair XP and is a good place to get Silver Unicorns, if you're doing the coin quest. Otherwise, between 50 and 60, I'd say it's a toss-up between this place and Forsaken Plains.
Mostly it was just a suggestion of one more place to consider. Comment: I came into the game in C4. I do occasionally see people working the various quests for A grade gear, but only occasionally. It seems to me like the drop rates are very low on the quests I have tried, and I suspect that most people have found other ways to get A grade gear, be they legitimate or not. It seems a bit of a shame to me that the quests aren't more useful.
Not only rare drops, but sometimes worthless rewards. I did the "whisper of dreams part 1" quest. After collecting 130 parts from two different 3X HP mob types (that mean a lot of partying), I got my reward. 2 maj. robe fabrics. Great reward. Keep them coming.
I would love for any field areas to drop herbs. Some of the ones that don't drop herbs give only modest XP and drops, at best. I don't see the sense in desgnating those fields as "party" grounds, because you see few parties in many of those places, unless they are bots. Cemetary, DV, Forbidden Gateway ...., all of those places really should drop herbs.
Ice Labyrinth drops herbs, and the quest there isn't to bad, at least your guarenteed A grade and B grade scrolls for your efforts. Assuming you want to stay there that long.