I use grab in Vietnam. I don't find much difference for me, except there are few credit card options. I don't find car or driver to be different, and haven't found either to be bad. There are, at least in my area, many more cars doing grab than uber. I asked the driver why he chose grab instead of uber, he said he gets paid daily with grab and uber is only once a week. Which is related to when I search for a grab car that will let me pay with card, I find none, but with cash I can find many more than uber.

However, from my limited experience and with friends, Uber is a little cheaper here in Saigon. Obviously not much in $$ since the fare is low to start, but if you use it daily as some do, adds up I guess.