Hello Alex, and thank you for asking such a practical question for weeknight cooking.
Between the two methods you mentioned, frying (specifically shallow pan-frying or sauteing) is clearly superior to boiling when it comes to both flavor and texture. Sweet potatoes contain a significant amount of natural sugars, and frying allows those sugars to caramelize, creating a rich flavor profile along with a wonderful contrast between a crisp exterior and a tender interior.
Boiling, on the other hand, often makes sweet potatoes waterlogged and dulls their natural sweetness because water-soluble sugars and nutrients leach into the cooking liquid. While boiling is simple, the texture is generally soft throughout, which is only ideal if you plan on mashing them.
For the most efficient weeknight dinner, I recommend dicing your sweet potatoes into small, uniform half-inch cubes. Heat a couple of tablespoons of high-smoke-point oil (such as avocado or light olive oil) in a wide skillet over medium heat, add the cubes in a single layer, season with salt and your favorite spices, and cover the pan for the first 5 minutes to let the steam soften the centers. Then, uncover and saute for another 8 to 10 minutes until they are golden brown and fork-tender. This gives you maximum taste and great texture in under 15 minutes.
I hope this helps you prepare a delicious dinner tonight!