Sometimes it's also a case of which pickup sounds better to you. Brand doesn't quite matter.
You are asking about Epiphone G-400 compared to Epiphone Les Paul right, not Gibson? If this is the case, they are having different pickups as you can see from the Epiphone website.
Sorry, i made such a mistake. I thought of Gibson straight away when i saw Les Paul. Now it's more logical to compare Epi SG to an Epi LP.
Epi vs Gibson is a no-brainer, depending on situations...