Sorry I misread your post. I thought you had a smart tv box. I don't have smart tv or xbox so can't advise on installation on these devices. I spent over a month doing free trials. There's plenty that don't even ask for credit card details. It's a great way to check out what's available. Which is the best one, probably depends on if you need the vpn for general use or something specific. I needed good speeds from specific countries and I found Nord better than Express for this. If you want to watch iPlayer etc. just make sure it offers the geo-located servers or whatever they call it. Not all vpns provide this service.
I'm looking for one that will work well for turkey, signed up for a month with this crowd for PL football to see how it works. €2 a month, can't go wrong. https://www.ssport.tv/
Haven't a clue about Xbox but I have express vpn on my windows laptop and the iPlayer works no bother through the edge browser.