Which is more valuable, gold or elixer?
Gold is generally considered more valuable as more upgrades require it where elixir is generally only used for research and troop hire.
I would say elixir is easier to acquire from raids, mainly due to the above point, it isn't used as much and therefore players usually have more stored up.
Look at this link in the 'Totals' subsection. It gives total gold at 2.8 billion, where elixir is 'just' 348 million. So by that logic gold is almost exactly 8 times as valuable (assuming you generate it at the same rate).