If you plan to run electronics or smart battery chargers, get a unit that puts out as close to a true sine wave power as possible. Most cheaper inverters put out a square wave, which makes some power supplies very unhappy. My el cheapo radio shack 300w won't run my charger for the Dewalt 18v tools because the square wave freaks out the brain inside the charger. I've heard of the same problem with some laptops.

Not responsible for advice not taken...