It would be handy to post a link to the actual page with the films so we can check them. What you have provided leaves room, as you have indicated.
MPEG2 is standard DVD format but given that a 4GB MPEG2 can squeeze down into a very viewable h264 of <1 GB suggests that they are likely of similar quality. Then too the mpeg4 is a precursor to the h264 and the same video would have compressed to the those two file sizes given the codec capability. In other words they are all likely equivalent though they may differ in other regards. h264 seems to me to produce a better quality video than mpeg4. If there is audio then differing audio codecs may also reflect in file size.
In the end it is really going to come down to what looks best to you, if they are otherwise of a similar picture dimension. Given the information you have provided and seeing the file sizes they basically look like what I'd expect for encoding a single video into the 3 different codecs. All are lossy so take whichever works best with your editing program to minimizing additional recoding steps in your final project.
If you had 3 files of identical size in all 3 formats then the h264 would be the best quality because the others would have had to have had considerable reductions in quality in order to have produced a file of similar size, with the mpeg2 probably being the worst. Basically a 4GB mpeg2 will compress to around 1.2GB mpeg4 and maybe 700-800MB h264 and you probably wouldn't notice much difference in playback quality on a normal TV.
