What’s best *for you*. How big do you want your master files to be, and how much information do you need to create the next deliverable?
Building on what else has been written, the most common, highest-quality per Gigabyte Quicktime wrappers are ProRes (422, 422(HQ), or ProRes 4444) or the AVID-centric DnX codecs. About a Gig per minute in 1080. There are higher-quality options, “Uncompressed”, and RGB sequential files in dpx tga and tiff format. These can get quite large (10x or more than the aforementioned), but offer different scaling strategies, in case you are considering film-out or DCI/DCP mastering. ProRes is by far the most common QT codec in general use on the Apple platform, but it is still a little bit Apple-centric, and for example may not be a good choice for Linux-based systems.
Unfortunately, the “democratization”, or perhaps more accurately “popularization” of commodity-based production approaches has been racing to the bottom with compromise after compromise while pretending to boost quality. The Long-GOP codecs like H264 may just be the least worst of this approach, delivering buzz-numbers like resolution size and data through-put, but seriously eroding any benefits in post-production by off-loading the responsibility to reconstruct the media stream with massive demands on GPU processing plus hollowing-out the overall robustness of the image values. I am talking about severely limited ability to carry over any color correction or multi-generational FX work.
H264 and other very low bitrate codecs should be considered “terminal” choices — great for distribution, streaming… comparatively speaking the “VHS” of the modern age. I don’t think anyone would ever have considered creating their masters in that format, and nothing has changed in that equation.
jPo
“I always pass on free advice — its never of any use to me” Oscar Wilde.