Yup the Cobalt leve is currently the best gil/time investment. If you can handle the extra time it takes to HQ then u can double your money. However it will take much longer. I think the math was approx 250k/99 HQ levequests.

I'd love to find out other leves but they all seem to be less convenient dealing with non-stackable items and far higher material costs. I can see the Mahogany Lumber leve being good as long as you have a BTN. Does that leve reward Mahogany Logs? If so it could be a good alternative if your running low on Ice Shards. However wind shards tend to be more expensive on most servers. So i think Cobalt is still King.