Hybrid grills are meant to operate on gas and charcoal, so you would naturally want to go with a model that works well with both fuel sources. At the very least, you will want a hybrid grill that provides consistently reliable performance regardless of which source of fuel you use.
This can actually be a bit more challenging than you would think. Some models that perform perfectly well with gas may not be as capable when using charcoal. On the other hand, some models deliver excellent results when charcoal grilling, but may deliver less than optimal performance when cooking with gas.
Safety should be foremost on your list of concerns. Look for a grill that has a secure and airtight seal for connecting with a propane tank or a gas line. Even though you will probably be using your grill outdoors, a gas leak can still be very dangerous, so make sure that the seal is absolutely secure.
A suitably large working surface is always good to have. Far too many grills have tiny little working areas that really aren’t very useful when grilling outdoors, requiring you to make too many trips from the work area to the grill and back. Think about how you plan on using your grill and what you will typically need during a cookout. Any grill you consider should have enough space to accommodate the ingredients and the servings you plan to cook up.
Finally, give some thought to the issue of durability. You will likely want to subject your grill to pretty heavy use, so you should reasonably be able to expect it to hold up to job. Despite your best efforts, your grill will probably be exposed to the elements, so make sure that the model you choose is built for rugged durability.