[Fyron]

You could do a forum search.

To sum it up, glassing is bad. When you can manage to do so, conquering worlds is far more efficient than glassing them. You get free population and facilities. Conquest is insanely easy in stock SE4. Even with a 50% ground combat trait, it is very, very easy to capture planets. A few dozen troops are enough to conquer most worlds, especially if you use Ground Cannons (Troop Weapons tech) or Electric Discharges (for Organic races) and a shield generator. Shield generators are not necessary, they just drastically decrease the number of troops you need.

Make sure that your troop transport ship has Capture Planet as it's strategy. If you assign it the class/type of Troop Transport, it will be given this strategy by default. Otherwise, you have to set it manually.

Of course, if glassing is your only choice to weaken a powerful enemy, go for it. Or if the territory would be impossible for you to hold for very long, but you still want to cause damage to the enemy, glass it. If you can keep it, conquer.