It's official: we'll use SI system to name IOTA quantities.
And which unit will you officially recommend to markets to avoid chaos?
The one that allow smooth and efficient trading.
For example, the minimum buy allowed on Poloniex is 0.0001 BTC
That is : 188.67924528 DOGE or 0.00495397 ETH or 0.04037679 XMR.
Exchanges will use the most practical unit according to their buy limits.