The best recliner for the elderly is one that is very comfortable but also has some kind of support built-in for your back. The best recliner for the elderly also needs to be easy to get in and out of, and it should have an adjustable footrest.
Manual ones tend to be cheaper but require more effort to move. The power ones are more expensive but are easier to move and allow for more flexibility when it comes to how you sit. You would want to prefer the powered ones as it is much easier for the elderly to access.