Is possible that coin like THEKEY go to 3 digit number per coin? THEKEY has total supply 10.000.000.000.
Is better to pick coins with lower supply or market cap if you're searcing high price of coin like SHIFT, ATLANT, BREAD?
Almost every coin which has price above 50 $ has low market cap and suppy (NEO, Augur, Decred, Populous...)
What's your opinion?

Market cap is a combination of price and supply and is the number one measure for valuing a coin. Based on that if you're looking for a coin to reach a high price it's more favourable for it to have a low supply.
Given your example, It's so unlikely that THEKEY will ever reach 3 digits, it would already then be at a 1 trillion market cap which exceeds the whole crypto industry right now.