Unfortunately, there is no one "best" NPK fertilizer for vegetables. Different vegetables have different nutrient requirements, and the best fertilizer for one vegetable might not be ideal for another. In general, though, a balanced NPK fertilizer with a ratio of roughly 10-10-10 or 20-20-20 should work well for most vegetables. You may need to adjust the ratios slightly depending on the specific needs of your plants, but this should give you a good starting point.