The Elder Scrolls V: Skyrim
I've slaughtered bears, necromancers, vampires, and dragons. I've learned to hurl blazing fire from a distance, and to sneak silently close before slitting my enemy's throat. I've toppled governments -- both local, and regional. I've forged armor, mixed potions, and enchanted weapons with the souls of my enemies. I've sprinted over grasslands, across frozen waters, up snowy peaks; I've delved deep into the ruins of ancient civilization. I've filled my home with books, gemstones, rare artifacts, and dragon bones. I've entered into pacts with demon lords from another plane of existence. I've logged over 110 hours in the world of Skyrim; and I still have more to do.
The amount of content in this game is simply staggering. And what it does best is continually surprising the player with new quests and points of interest, seemingly out of nowhere. This is how I took over a hundred hours doing what "can" be done in about two: getting requests from NPCs, happening upon suspicious notes, stumbling into some ancient ruins, and always spiraling out into more and more quests. So I ended up running countless errands and championing dozens of other causes, instead of doing that whole save-the-world thing.
Around the 70-hour mark, I decided to stop intentionally taking new quests, and took another 20 or 30 working through most of the remainders, before finally getting back on track with the main questline. But even after spending more time with Skyrim than I have with (almost) any other game, I still have more work to do with the Thieves' Guild, an unfulfilled date with the Dark Brotherhood, and entire cities I've barely visited (actually, I never visited Falkreath at all!) -- which is all not to mention the seven more experience levels I need to get to 50, the handful of Daedra lords I have yet to meet, and the level-100 Destruction spells, which I've learned but don't have enough Magicka to cast yet!
And I dare not dream of all the content that's popping up on Steam Workshop.
I never used to understand how people got hooked on Bethesda games before, but I think I finally get it, now. They can appear boring to watch because the immense reach and density of content seamlessly integrates you into the game world, such that even tedious and commonplace activities are all part of the adventure. And by being immersed in this world, continually distracted by quests and events, it becomes surprisingly easy to overlook, and even forgive, their games' technical issues.
It should be a foregone conclusion that basically everyone already knows this by now, but: you should play Skyrim. If you want melee combat in your RPG, you should probably look into Kingdoms of Amalur instead -- otherwise, pick up your bow or your spell tome, clear out your calendar for the next few months, and fall head-first into what may be the most engrossing virtual world ever created.
Oh, and always keep a finger over the quicksave button (F5). When a boss unexpectedly kills you and the last automatic save was an hour ago, you'll be glad you did.
Better than: basically any other role-playing or open-world game
Not as good as: I'm still partial to GTA4, but all bets are off if Bethesda figures out how to put guns and cars in Tamriel
Now I want to try Oblivion: buuut I'm pretty much all RPG-ed out for a while
Progress: Level 43 Dovahkiin, Harbinger, Arch-Mage, Nightingale, Storm-Blade