My opinion is that Unity is doomed, for the price of Unity pro you can buy UE4 license, 75 times. If you are actually selling, UE4 is less initial investment, and that 5% is only more than Unity price when you are actually earning big amounts of money (in my opinion, if i get enought success to lose money with that 5% instead of unity pro, ill be really happy, and 5% is low comparing with the 30% steam takes)
I find UE4 a better engine overall, but Unity wins in the mobile/2d department, as its a MUCH more lightweight engine. For medium to big 3d games, UE4 wins, Also i find programming in ue4 be amazing as i can see into the source code if i dont know what something does.