As posted above, key question is what you like to shoot, that would determine the body most suited.
Sharing my experience, I decided on a D800 as it covers all my needs. I shoot landscape, portrait, personal indoor events, birding, long exposure night. The DX mode @ 5fps works fine for birding. I don't shoot high speed sports, therefore no need for >8fps. Happy camper with the D800. Even with the high iso disadvantage, down-sampling the huge 36MP to the D3S equivalent may result in very good pictures. One downside is the huge RAW files, which sucks up lots of storage & processing power if you do PP. Hope this helps you in your decision...