Does the person have a leg length difference, specifically, from the knee to the heel? If yes, consider individual footrests that can be adjusted to accommodate both leg heights.
Does the person have special transfer considerations? Do they need to use the footplate to help get in and out of the chair? If yes, consider a one-piece footrest which provides more surface area for the feet.
Does the person need to elevate only one leg? If yes, consider a footrest that can raise and lower.
Does the person have limited ankle and/or knee range of motion? If yes, consider elevating legrests with angle adjustable footplates.