There are many options when choosing a gas grill; however, there are three important qualities every gas grill must have:
Even heat distribution
Every griller knows that hot-spots are the worst! A grill with really hot areas and some cooler areas makes cooking very difficult. You should be able to move your hand over a gas grill and not feel much of a difference in temperature throughout the grilling surface.
Gas grills should last for many years, not just a few seasons. That means they should be built from heavy-gauge and corrosion-resistant materials. Generally speaking, if a grill looks or feels like it is poorly-made then it probably is going to let you down within a year or two.
You should be able to use your gas grill with children nearby and not fear a gas leak or flare-up. This means the plumbing and fittings must be secure while fat and juices from your food must be directed away from the direct flames.