Drive is definitely cheaper and more comfortable if you have multiple persons. But if only one person, ETS is more convenient since the cost savings not that much and you can relax in your seating instead of having to drive alone.

The train schedule seems to tailor for people going to Singapore for a quick business related trip. For example, start at 7:45am and reach Singapore around 1pm (after immigration), then go for job interview in the afternoon and take the train back at 16:20 and reach KL at 20:40.