I'd Say Final Fantasy XIV

I'd suggest Aion, I loved that game but I couldn't play it anymore.

Get Shadow of Mordor, you can check out my review here

Shadow of Mordor is okay, but its really repetitive. I love open-world games like Skyrim, Fallout, and Assassins creed, but Shadow of Mordor didn't quite feels like any of those. It's worth a try though you never know.

Middle Earth: Shadow of Mordor is a really fun game as many others have suggested. The core gameplay mechanics are simple yet the revenge based gameplay and central plotline are interesting and it should give you around 30-40 hours of play. The open world is also really fun and there is a lot to do when roaming around

Whilst not fully open world give the Mass Effect Franchise a look. Each game features a very interesting plotline, fulfilling gameplay, an excellent moral choice system, character customization and a ton of content. I dumped around 50 hours into each game in the trilogy and avidly enjoyed each of them. With Mass Effect 2 being my favorite

If you don't mind simplicity i also suggest giving the Fable Trilogy a look. Whilst character customization is extremely limited and the difficulty is quite low each game is still really fun and great if you like open world role playing games. Moral choices are abundant and each game should offer you a 30 hour experience with a high level of reliability. Out of the 3 i personally suggest Fable 2 if you are on a tight budget, but you can prob get all 3 from gamestop for $20 these days

The Dragon Age Trilogy is also something that you shouldn't ignore. Apart from the avid disappointment that was Dragon Age 2 (which was still fun, yet fell flat compared to biowares typical quality standards) both Origins and Inquisitions feature in depth lore, fun tactical based combat, an open world to explore, class specialization, character customization and an interesting main storyline and sidequests. Origins offered me around 100 hours of Gameplay whilst Dragon Age 2 offered me around 30. I have yet to finish Inquisitions

Also if you have yet to play it, try Final Fantasy 7. Dear god that game is just amazing in most respects, can run on most low spec machines and can be purchased for a good price on steam (especially seeming that sales are on at the moment).