Personally, I would go for a RPI4 model B and a wireless keyboard touch pad combo if You are interested in a RPI system. The 400 means you're keyboard is wired

Personally, I would go for a RPI4 model B and a wireless keyboard touch pad combo if You are interested in a RPI system. The 400 means you're keyboard is wired to the TV, which for a media center isn't that great. If you are also having to buy a monitor it might not be a bad Idea to look into black friday laptop deals too as a 400 plus monitor is getting fairky close to the price of a low end acer or asus. Almost all laptops have an hdmi output and far more horsepower than you will get from a Pi.