Looking at other successful coins I think we should keep it well under 21 million.

Cut the subsidy so we're bleeding under 150,000 coins per month rather than 1 million and that will allow us to continue PoW for years while also maintaining PoS which is another feature people seem to like right now.

Personally, looking at coins like NAUT and a few others, I would say cut the max as close to 10 million as possible, but I'm not sure if that's possible given we're probably close to 6 million right now.

Remember, the formula for Currency value is simple and straight forward:  Price = Transaction Volume/Velocity + 1/Supply.

It will take us a while to significantly increase the number of Transactions while decreasing Velocity so the only other variable under our direct immediate control is Supply so we should do our best to reduce supply as much as possible as soon as possible while maintaining a viable PoW/PoS reward protocol.