Unless magic somehow works like haki to let Laxus hit Enel, the only way he can actually hurt Enel is to eat him. Enel on the other hand DOES have ways to hurt Laxus other than just electricity (which Laxus can eat). Such as using his staff, reshaping the staff into a trident for piercing attacks as well as forging other metal in such a way if he desires, etc.--all the stuff he did against Luffy in their battle once he realizes that electricity won't work on his opponent.
Since we have no evidence that Laxus has any way to hit Enel, and there's no way that Laxus would actually eat a freaking human, I have to give this to Enel via his intangibility and melee attacks. As soon as he realizes his opponent powers up by eating his lightning, he wont' use his lightning anymore, and he'll proceed to lay the smackdown against his opponent who cannot even touch him.
In summary: Enel Wins.