Best CD of Rachmaninoff's Third Piano C

Kitch, no the remastered Davis/CBO Berlioz Sym Fantastique is a single disc, part of new "50 greatest" series just released at mid price. Contains only Sym Fantastique like original release, no additional music.

The disc you refer to is an older Phillips "duo" release.
The "50 greatest" series was just released and uses SOTA 24/96 remastering which at least in this case delivers as advertised.

I saw several places on the internet where you can order the
complete Rach PC 1-4 Ashkenazy/Previn/Decca for under $14
as a budget priced "Decca Double" release. Life is good.

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