Potash - ELM GMM TRH STB

I bought 3 potash companies when BHP put in a bid for Potash Corp. ELM mining in Congo has gone up by over 3x, GMM hit nothing like potash but this is outside the expected zone and the market didn't like that news (strange!), and TRH has gone up and coming down towards my buy price.

So how would you pick which stock if there was only one to choose? In a year's time, I think there will be little differences. In the meantime, STB (bought before the BHP bid) has found lots of it in Eritrea and has gone up exactly 10x my average buy price of 28.8c to $2.88.