Final Fantasy XIV is a great option, and it doesn't require a huge time commitment unless you want to take on the Ultimate content, which is limited to just a few bosses per year. The game also has one of the best stories in the Final Fantasy franchise, and you don't need to be a fan of FF to appreciate it. Aside from FFXIV, World of Warcraft and Final Fantasy XI are also solid choices. I heard about New World, but the players of that game seem to hate it more than anything else.
Discussion
What do you think about TES online ?
I've never played, but if I go by what they told me, it seems like the opposite of FFXIV, which is more open to non-FF fans. It seems geared towards people who really enjoy The Elder Scrolls, Skyrim, more specifically. It seems more casual, too.
I also forgot about Guild Wars 2, that game is really fun and has a do anything you want approach. Wakfu is also a decent strategy MMO, but it has a mobile game feeling to it.