I think the best route probably depends on the time of day [and the day if landing on Tues during Carnival days in Grand Case]. Weekdays later in the day, really busy through the Dutch side - bridge and causeway openings also affect traffic later in the day.

failing that the Marigot route has Super U - pretty good. Not so happy with their rum selection,fabulous if you are a Coke fan [pretty much an entire aisle!], but no cans of club soda. Otherwise good selection of most items.

Dutch route will take you past the Carrefours, more American and generally well stocked

J&B