Usually value per coin is not a very useful metric, because some crypto's just have a higher number of coins in circulation. Market cap is a more fair way to look at them.
However, if we consider the the psychological impact of the higher numbers on the ehm... less informed investors, there may be some use to it after all.

Oh, and to answer your question: ETH, DASH and ZEC are all in 3 digits already. Since the potential of coins is hard to predict, my bet is on these three since they'd need less of a boost to get over 1000 per coin.