Which is better? Walk in tub or shower conversion?

[HandyGal]

My dad will be 80 soon and is visually impaired, but in good health so far. I was thinking of attempting a walk in tub install or putting in a walk in shower with a fold down seat at his place. Which is better and why? He's not a techy guy, so if there's a lot of controls to confuse him operating a walk in tub it might not be for him. What's your opinion on these 2 options? I'd love to hear them!