Pellets
Pellets are a great choice for the normal betta owner who only has a few bettas. Specially designed for bettas, betta pellets provide a near complete diet, especially Betta Bio-Gold. All you need to do is get a few pellets and drop them in and you're done. Easy as that. However, your betta may not go after it right away, especially if the betta had a taste of bloodworms. This usually isn't that big of a deal since most bettas are raised and fed pellets since they were fries.
Veggies
Lastly: veggies. While bettas have no dietary need for these foods, they may have some healthy benefits if fed occasionally and in moderation; cucumber and de-shelled, cooked peas are a popular remedy and preventative for constipation, for example. They do not need to be a part of a betta's regular diet, but when fed sparingly, appear to create no adverse side effects.Conclusion
If you read the above, snorted, and thought "well that doesn't help me; I still don't know what to feed!" since every food type's positives and negatives were explored, please consider the following. Most animal nutritionists agree that the best way to ensure complete nutrition for your pet is through variety. Because each food as its fortes and failings, it is best to feed multiple foods; this will magnify the benefits and reduce the negatives. What's more, feeding a great variety of foods is more enriching for your betta, providing a valuable source of stimulation.It is also suggested that bettas be fasted at least one day weekly. Because bettas tend to have a dry food as their staple, and a very high-protein diet, they are prone to constipation. While the feeding of a mashed frozen pea is good for clearing up constipation, prevention is always the best medicine; fasting once or twice per week typically offsets digestive problems in average bettas.
When you feed your betta a variety of food, you get one healthy betta.