Liquidity isn't a question of how many coins are in circulation numerically, it's a question of how much monetary value there is across the entire coin supply. The coin with the most 'liquidity' is therefore the one with the highest marketcap, not the 'most coins'. Emission curves don't have jack to say about liquidity unless the valuation is there to support it.
Yes the most liquid coin is the one with the highest marketcap, but the coins that are in circulation numerically are also important. If you have a coin with 101 tokens worth 100$ each(marketcap of 10.100 $) , but 100 of these are taken out of the ecosystem because of some service that locks them up, you only have a liquidity of 100$.
In case of DRK the 'liquidity' would be ca. 9.300.000$ right now if you don't count the coins which are locked up in masternodes.