2 questions to answer:
1) How much space do you want a DVD to consume on HDD?
2) What format(s) will your device be able to handle?
If space is not a primary consideration, then a full-sized ISO or VIDEO_TS folder is the ticket. Simple and fast, and it preserves all DVD content, menus, extras, etc.
If space is an issue, then you can do several different things. The MPEG-2 (VOB files) can simply be put into an MKV container with original audio. This is a "movie only" approach and eliminates all other content on the disc. The main title can also be converted to MPEG-4 and put into a MKV container, again with original audio. This consumes a lot of time and CPU resources since the conversion is slow. Other formats are certainly possible, like MOV (Apple).
For the "big screen", the best option is one that does not degrade video quality, such as ISO or VIDEO_TS folders.