Best CD of Rachmaninoff's Third Piano C

I can also recommend V. Horowitz/CSO/F Reiner for Rach 3 (RCA, 1951 recording). There is a later recording of Rach 3 with Horowitz/NYPO/Ormandy (RCA, 1978). I prefer the older version.
I have both on vinyl, so cannot give the CD refs -- sorry.

The Horowitz/Ormandy is one of the references Gramaphone Magazine uses to compare with others. Probably worth a listen.

The Volodos recording won numerous prizes.. for a reason! Not only is the recording quite brilliant,  the performance is superlative. Definitely my favourite in an extremely crowded field. 

I haven’t heard to many new recordings over the last 15 years or so.
The first criteria should be, which cadenza?  Rach wrote a short and a longer one.  For me the longer, stormer one is essential, the emotional heart of the piece.  The famous Horowitz recording actually uses the shorter one.  My favorite was made about the same time as the Horowitz/Ormandy, with Azhkenazy/Ormandy and the Philadelphians.  For the shorter cadenza, try Earl Wild/Jascha Horenstein and the Royal Philharmonic, also an audiophile recording 

Speaking of the cadenza, my favorite was an old recording with Andre Watts and Ozawa (NYPO), who combined the two cadenzas--the short one for the first part, the longer one for the second part. That recording also cuts out some parts of the second and third movements, though (I think Rachmaninov himself may have made those cuts, as he often did that to his works when he worried they were too long), which I kind of like, but others may not.  I heard them play the work live at Hill Auditorium in Ann Arbor when I was at school in the late 60s and, have been hooked on the piece ever since.  I still like Argerich/Chailly for the short cadenza, a fantastic live performance, and  Ashkenazy for the longer, more brooding one.