Investing £1,000 GBP a month, All in ETH or should I put a bit into OMG

If I invest 1000 GBP a month, do you think I should put it all in ETH, all in OMG, or if both, how should I divide it between the two and why?

Interested in what people think. Thanks.

EDIT: Also worth noting I already have a decent amount in both.

EDIT 2: Please do not recommend other coins besides OMG or ETH. I'm only interested in how to divide my monthly funds in ETH and OMG only. Thanks