Really? I don't know, I think I have gotten bored of Mental Ray. After using something for 2 years , you tend to get bored of it. Well, ATM, Indigo is my thing. Now, I am trying to get Maxwell Renderer now. Results= much better, speed = much faster.
Anyway... I like the quality of Indigo renders. So, I think it's mostly personal preference.
Live the life you love, love the life you live