When it comes to open world RPGs The Witcher 3 is my gold standard for quality. The game-world is absolutely massive and the majority of the locations are well worth visiting; the graphics are some of the best you will encounter in any game today; the characters are well written and quite complex; and most importantly, none of the side-quests are designed to waste your time by making you collect a dozen bear asses. That doesn't mean you are going to save any time, however, as The Witcher 3 has already robbed me of well over a hundred hours, and because I hate seeing other people have free time I would like for you to discover how fun it is as well.
Since showcasing this through words alone is pretty much impossible, allow me to instead present you with a bit of gameplay. The video below contains a single, random quest I encountered in the middle of nowhere and like the majority of the classics it all begins with a giant wolf, a fat man, and a bleeding tree. Have a look, its a rather entertaining one:
If you're interested in a more detailed look at The Witcher 3 and why exactly I believe you should give it a try, head over here.