Which format to keep: TS, DV, MOV, MPT, MP4 or M4V

Hi!

I digitalised our home movies ten years or more ago when using Microsoft Windows. I later moved to Ubuntu and then to Apple. Over the years I have used various versions of iMovie and QuickTime Player.

The result is that I have accumulated two, three sometimes even four copies of the same movie file, all with different formats. I would welcome advice as to which format I should keep and which I can safely delete because they are taking up too much space on my hard disk.

First of all I have a folder with a movie in MOV format plus files for iMovie Cache, iMovie iMovie (sic) Cache and iMovie Thumbnails.

In addition I have the same movie in one or more of the following formats: TS, DV, M4V, MP4 and MPG.

Which format would have preserved the best image? In all honesty I cannot see any difference between them, but that may just be my eyesight or my lack of practice.

Now that I have retired I hope at long last to edit these films in iMovie and produce videos that I can pass on to our children and friends.

Thank you in advance for your advice!