There are a lot of considerations when choosing a baby gate for stairs. Here are some of the more important ones:
Where you plan to put the gate matters! Simple swing-open gates are great for doorways and at the top and bottom of stairs. But the ones that are tension-fit require walls on each side to support the outward pressure; do not attempt to install these tension-fit gates in situations where one side is a wall and the other side is a railing post (like at the top or bottom of stairs). The outward pressure will push the railings to the side and eventually give you a wobbly railing. Also, do not install a gate at the top of the stairs if it has a bottom (step-over) rail - this is a serious tripping hazard, and should always be avoided. Because of these different uses of baby gates, below we categorize gates by their primary uses: ordinary/doorways, versus top-of-stairs.
The gate needs to be sturdy! Babies will amaze you with their ability to foil all your best attempts to keep them safe. They will try to pull the gate, push the gate, climb the gate, lean on the gate, or bite the gate! All of the gates recommended below are rated as the best in terms of sturdiness, to help you keep your sanity when you can't have your eyes on baby 100% of the time.
Little fingers pinch very easily! We don't recommend any of the wooden expanding gates, or the gates with the pressure locking bars. These increase the risk of finger pinchings, and in some cases lacerations, and should be avoided. But if you have a pet-only home and you're trying to keep your dog in certain areas, they're quite good for that purpose!
You want to open the gate with one hand! Carrying the baby? A laundry basket? Groceries? Talking on the phone? The last thing you'll want to do is put something down because both hands are required to open the gate's locking and swing mechanism. All of the gates recommended below have well-reviewed locking mechanisms that can be opened with one hand. It's a complicated trade-off between making it difficult for a baby to open, while keeping it easy enough for an adult to open with one hand. This usually means the locking mechanism will require larger hands to grip and pinch/rotate/slide. As a result, some adults with smaller or weaker hands (like older relatives) tend to have some difficulty with modern gate locks.
Make sure your doorway isn't too wide! Some baby gates come with extensions to accomodate larger doorways, but other gates do not. If your door opening is greater than 31" wide, then you will likely need at least one extension. So keep this in mind. In our recommendations below, we provide specifications regarding door widths and when available, links to extension kits that fit the application.