Xbox has this deal going where you can convert an Xbox gold membership to Xbox ultimate for free (or $1).
You can convert up to 3 years worth of Xbox gold. You can only buy a 1 year subscription from the game store, so if you want to do all 3 years you have to buy 2 more 1yr subscriptions from amazon (you get an instant code, then just add both to your Xbox account).
1 year of Xbox gold is about 1/3 the price of 1 year of Xbox ultimate so it’s a good deal.
Game pass has a bunch of games (at least 100-200 at any given time, with some big name titles (NBA 2020, Witcher 3, Grand Theft Auto 5 (best game ever!), they even have some of the PlayStation yakuza series up right now). I’m definitely enjoying it, and for what averages out to $4.99 a month it’s worth it for me, especially right now.
You can only do that $1 deal once though. So if you want to do it and get the most for your money just make sure you add your Xbox gold subscription first.