My favorite taxis are the green ones from the Mai Linh Group. They do have the best reputation and seem to be a little more reliable than other companies. They go by taximeter and 1-2km are around VND40-50k.
Another alternative can be one of the million white Vinasun Taxis. They are often quite reliable even though funny (not so funny) stories seem to happen with this company. They go by taximeter and 1-2km are around VND40-50k as well.
*To avoid inconvenient rides with taxis, scroll down to my safety instructions at the bottom of the “Saigon Insights” list.