Forks, because with a fork and knife you can conquer almost anything the culinary arts throws at you. That versatility can't be matched by chopsticks imo.
Chopsticks are better at handling most food items except for meats that require the use of a knife. The one exception is fish. Especially when eating whole fish, the chopsticks give you the dexterity and precision necessary to grab the meat flakes off the bones and fish-head that a fork just cannot provide.
But only bamboo chopsticks are any good. If the chopsticks are plastic or metal with no gripping texture, then a fork is probably better.
i think it depends entirely on the cuisine. for almost any food in east asia, you're better off with chopsticks. for any kind of stir fry, whole fish (as @millais rightly points out), noodle bowls, dumplings, and so on, chopsticks are vastly superior. (good luck eating a bowl of ramen or worse udon with a fork.)
forks are only necessary where cutting food is necessary, but this is not an experience in asian cuisine where the meat is supposed to be cut by the chef already. for steaks, whole potatoes, or whole roasts where you're getting big pieces of food on your plate, you need a fork and knife.
one thing that I think you're universally better off using chopsticks for is noodles, and yes i mean spaghetti, linguine and the like. chopsticks are just objectively better for eating noodles than forks are. (smaller macaroni style noodles not so much)
I've been told that chopsticks are healthier because they take longer to get the food to your mouth, so you have more time to chew in between mouthfuls. That being said, I personally prefer forks because they're easier, and I tend to drop food with them less often.
Forks are just a better tool, period. Chopsticks are not as good, and part of a culture that doesn't have the same ideals. That's fine they look at food a different way. I enjoy asian dishes, but guess what? It's still better with a fork.
