How much weight you can lift? All-terrain strollers are heavy, and you may need to pump some iron to lift double all-terrains. Make sure you can at least comfortably lift the stroller into your trunk.
Do you walk or jog? If you jog, look for an all-terrain stroller that is also a jogging stroller. Read the owner's manual or check the manufacturer's website.
Do you want to use the stroller with a young infant? Some all-terrain models have fully reclining seats, but many don't. You may have the option to use a car seat or bassinet, but you'll want to check first.
What are the dimensions of your trunk? All-terrain strollers can be bulky. Be sure to measure your trunk so you know whether the folded stroller will fit.
Try before you buy. Is the stroller easy to push? Does it maneuver well? Is the handlebar comfortable? Take your children and see if they're comfy. If you're buying a double, is there enough separation between seats? Does the stroller still feel balanced with a baby and an older child?
Consider older models. Once they have a winner, many stroller manufacturers will tweak very little about a stroller from year to year. They may only add different color or fabric choices, or redesign one small part. You may be able to find an older model more cheaply without sacrificing performance.
Buy used with caution. Buying used at a fraction of the price may sound appealing, but all-terrain strollers are subject to a lot of abuse. Like other strollers, they're also subject to recalls. Make sure you know the stroller's history, or your good deal could be a mistake in the long run.