What type of weapon should you use: Small guns or energy weapons?
Well, Energy Weapons are certainly more commonplace in the Capital Wasteland than the Small Guns. Sure, both are very easy to find, but the easiest type of weapon to find are the energy weapons, with the Laser Pistol available early on at the Super Duper Mart. Protectrons and robots are easy sources of energy weapon ammo, as well as the Enclave and Brotherhood of Steel. Energy weapons are by far most accurate, durable, and have higher criticals.
Small guns, in the other hand, are significantly more powerful. A conventional Assault Rifle is more harmful - in terms of damage - and can hold its own even against the more powerful Plasma Rifle.
In conclusion, Energy Weapons is the best option in order to survive more easily out there. It has many more advantages than the Small Guns - even though Small Guns tend to have a higher damage- and is easy to find. In other words, you won't have to worry about running out of weapons when you are using an Energy Weapon.