The renders shared so far look amazing.
I been hearing a lot of good things about RS, but haven't had the opportunity to give a try. I tried Corina the moment and the results are not that bad, but I think that compared with redshift, people are saying that it's easier to get something looking good in RS.
I been using Arnold lately and so far so good, but render times can get stupid long if you not careful with light samples.
I haven't tried Octane yet, but I do like the look of the renders. I might give a try later.