The best bang-for-the-buck Cinema 4D Workstation currently (03/2017) would consist of the following hardware components:
The Best CPU for Cinema 4D: Intel i7 6700K or i7 7700K
Many Cinema 4D features like deformers, generators and cloners are calculated on the processor using only a single-core. This is where you will want the fastest possible single-core speed. The Intel i7 6700K and i7 7700K 4 GHz – 4.2 GHz and some more Turbo GHz to make the viewport refresh as fast as currently possible. With decent cooling, you can also overclock these.
RAM: 32+ Gbyte DDR4 (Look for high Clock Speeds, low CL latency)
RAM is quite cheap nowadays RAM prices have unfortunately increased in the last couple of months but 32GB helps when you have large scenes (high polycounts, displacements…) and textures, or multiple Applications open.
Graphics Card: Nvidia GTX 1060
There is no need to get an overpriced Nvidia Workstation Graphics Card (Quadro). Since the bottleneck in viewport speed is almost always the single-core cpu speed, a “Gaming” Graphics Card such as the Nvidia GTX 1060 8GB will be more than enough.
If you are planning on rendering with your GPU (Redshift3D, Octane, VRAY RT …) you should consider the Nvidia GTX 1070 8GB, 1080 8GB or even the 1080ti 11GB. The important part here is how much VRAM do you need to render your scene and can your render engine use system memory if the scene is larger than the VRAM.
The GTX 1070 and 1080 have dropped in price quite a bit and you get 1920 – 2560 cuda cores of power on 8GB of VRAM.
Mainboard: Asus H170-PRO (Intel i7 6700K CPU), Asus Prime Z270-A (i7 7700K)
HardDrive: Definitely go with the new M.2 form-factor such as the Samsung 950 or 960 PRO/ EVO. These are blazingly fast. Be sure your Motherboard has a socket that supports pcie speeds on M.2.
This Workstation will give you roughly 950 – 980 R15 Cinebench Points, which is still very good for rendering. This PC though was configurated as a Workstation and not a render-node, meaning: “As little delay as possible while actively working on Scenes”. If you are looking for fastest render-speed the Processor configuration will have to go into a different direction: Max CPU Cores (e.g. Dual Xeon E5 2630v3 or i7 6800K – 6950X), but this will then be slower for actively working in the viewport and more expensive.
Check this Link for CPU Single and Multi Cinebench Benchmark Scores of all modern CPUs: http://cbscores.com/index.php?sort=single