There are so many great SXM restaurants that this is a difficult question to answer!
We go almost every year, and here are some of our favorites:
SkipJacks in Simpson Bay for great seafood.
Antoine's in Philipsburg, nice French in a quiet atmosphere. Be sure to order one of the dessert soufflés,
Le Moulin Fou in Maho for more contemporary French. Love their goat cheese salad.
Le Belle Époque for fresh mussels when they are available, crisp pizzas and other French dishes at Marina Royale in Marigot. Also Tropicana at the Marina, but you often need reservations to get in.
Mark's Place by the Grand Marche near Philipsburg. Not much for atmosphere but good ribs, fish and other local food and a very reasonable price. If you're in a timeshare, it's good for take out..huge servings so leftovers for a future lunch or dinner. They do a booming take out business for locals.
For beach bars, there are lots of great meals for lunch at Orient Beach. Chez Leadra has nice sandwiches and wraps. For more upscale French, Kakao has a lovely setting, and you can get good salads, pizzas and burgers if you want more casual food. I haven't tried them yet, but have heard good things about Dream. bar on Nettle Bay and Kokomo in the new development on the bay before you get to Little Bay by Philipsburg.
Of course, Grand Case has a reputation for many very good French restaurants. We don't go over there for dinner often because we travel to SXM in the winter and prefer not to drive those roads in the dark if we can avoid it. We did have a very nice dinner last year at Piazza Pascal, which is Italian.
If you want even more suggestions, read through the trip reports and discussions at the SXM bulletin board on Travel Talk online. Lots of restaurant discussions, although we don't always agree with some of the popular choices there. Some of the posters are big on restaurants where the manager is their "buddy" and food is less important, like Pineapple Pete's, which we've found kind of disappointing several times. There are also others who prefer more standard meals, like steaks, so they love steak places like PegLeg pub, while we figure we can grill a great steak at home and want more interesting meals. But it's all a matter of preference, so you can read for some viewpoints. The group is also hot to know what's new, so they can forget classics like Antoine's on favor of what's just opened. Here's the link.
http://www.traveltalkonline.com/forums/postlist.php?Cat=0&Board=stmartin