I reckon the difference between the Liquid Spark and the Atom is such that if you look at the measurements, Atom wins hands down. But can you actually audibly hear a difference? I'd say 99% of cases you can't know which is better if you A/B test them blindly. But theoretically Atom should perform better.
If you consider that they both perform well, then you should take a look at the price... and it's the same.
Next, the looks and build. Well, many seem to prefer the metal of the Spark but I kind of don't like the non-rectangular shape of it.
What might tip the scales however is the customer service and communication, which JDS Labs has nailed down. I just had a discussion with their representative and I was left with all my concerns answered, educated and got to say quite impressed! Oh and somehow I'm craving for that Element and it's big knob now even though I literally just got the Atom two days ago