Hey there!
I happen to own both of these wonderful products.
I would say that they both incredibly well. But it really is down to you. Do you want portability or a wide soundstage?
The thing is, the LCD2 cant really be used out on the street, whilst the ES5s can be used at home as well as when you're out and about.
In terms of sound I would say that they have some differences, the soundstage of the LCD2s are much larger but this is to be expected with headphones. The bass of the ES5 is more powerful and dynamic but the LCD2's bass is more enveloping.
The mids of the ES5 are much smoother and brighter than the Dark LCD2. If you're a huge fan of vocal Music I think the ES5s will be better off for you.
For the highs and details of these two products I think that the LCD2 has the upper hand on this.
Anyways in short I would say that if you want dynamic and punchy bass, with bright and smooth mids go for the ES5!
If you want deep enveloping bass and a wide soundstage go for the LCD2!
But on a side note, the ES5s sound great just out of my iPods Headphone out. Whilst the LCD2 requires good amping for it to truly shine.
Anyway the choice is yours, You definitly wont have regrets if you buy either product
Happy headphone/IEM hunting, Hope you have a great time with either one
Cheers,
Arrigo.