500GB. I wanted to get more storage but then i realized that with 1gbit internet connection, i dont need it, i can download whatever i want in a few minutes. Fast internet is a game changer, it allows me to try and test games without thinking about it.
I also have a 2tB hdd for media but i dont use that to store games.
Youtube has better quality and rewind but twitch has more interesting chat, even if it is just spamming emojis. Twitch chat has a vibe, feels like you are in a stadium. Also for gaming streams, twitch is a must. Also you need a browser extension like 7tv to appreciate the chat.