I did not try Esenthel but it looks like really impressive
Ratchet claims that it is even fast
So, it comes the question
Why should we pay 1500 usd for Unity while Esenthel,C4,Leadwerks, DXstudio cost 150-200 usd ?
Attention...I am not ironic
I am pretty sure that marketing played a key role but it is hard to assume that it is the only reason of the Unity tremendous success
I sincerly want to know whether Unity actually provide some substantial advantages over the above mentioned engines

Has anybody been using on extensive basis Unity and one or more of the other engines ?

Thanks in advance for your feedback