Assuming you mean legally, the best options are Paramount+ (or whichever service it's on outside the US) or on Blu-ray. None of the television series are available in 4K to my knowledge, but the movies are.
? I prefer the original special effects, but that's what I grew up with and it gives me the most comfort. I think the only way to watch the original is with the blurays at this point.
Back in the day prime used to have both available for streaming, but the golden era has ended.
If you want the highest quality video and audio the Blu-ray is the best you can get.