The Witcher 3 is the best RPG in the last decade.

[Mummelmann]

I agree with OP, it has placed itself on my top 5 games of all time and even made me finally take the plunge and buy the books.

Most big RPG's have at least one major issue for me, examples:

FFXIII was just not a good game, period. Poor story, enclosed gameplay for 15-20 hours, semi-automatic combat, anonymous music, annoying and severely stereotype characters etc. The only redeeming factor was the visuals.

Mass Effect became more and more a shooter, they even removed a bunch of skills and the entire inventory, the story although expertly told, is a very cliched sci-fi one with few original moments. Battlestar Galactica, Babylon 5 and others did it before (and better at that). The combat also became way too simple and the only reason it was harder in ME 1 was that the controls were kinda poor.
The side quests, especially in the first two, are beyond terrible, the first game took so far as to use the exact same template for every single planet down to the positioning of the enemies and the layout of the room they were in and the Mako vehicle has the most insufferable controls I ever came across, I was shocked that a company like Bioware would ever release an RPG with side quests this atrocious.

Skyrim: a great game no doubt but the sense of scale is ridiculous, the "epic conflict" between Nords and Imperials becomes a 20-man melee in a village. The dragons are sorely underpowered and way too easy to defeat, you become overpowered no matter what you do and the Sneak + Bow combo is downright broken as a game mechanic. They took away a bunch of skills and added perks, which cause the most serious overpowered mechanics. Leveling is way too simple, I was around 55-60 after 50 hours of play, compared to level 19 in The Witcher 3.
The entire game is just too easy, few enemy types and most locations look almost identical, I lost count over how many orange tombs with Draugr I cleared out, only to find the same loot and a few gold everywhere.

Gothic III: Actually my second favorite of these games, after The Witcher 3, but not without its problems. The controls are a bit whacky, especially in melee, the archery part is actually better imo. The music is sublime but the voice acting is often terrible. The side quests are rather boring, almost as boring as Skyrim and Oblivion. Nowhere near as bad as the first ME though.

Dragon Age: Inquisition I have yet to play but I'm getting it some time this year, most likely near the holidays.

For me, nothing comes close to The Witcher 3, the care and precision laid into side quests, the voice acting, dozens and dozens of interesting characters, the thrill of doing the contracts that are a few levels above yours, the slowed progression that forces you to focus more on tactics and timing to survive rather than gaining superpowers early on or midway, like most RPG's.
I cannot find a single major flaw in this game, and after about 50 hours of playing; it's not for a lack of trying.

For me, it's not only the best RPG of the decade, it's right up there with Baldur's Gate II, Deus Ex and even Betrayal at Krondor, which is my all time favorite game. It is mindblowing.
Most complaints I've read are about level progression and controls; there is nothing wrong with either, they're just not made for people who find Skyrim or ME challenging enough and require actual thought and skills.
Skyrim and Mass Effect, for all their strengths, have no combat systems as such; you press a button and an attack happens, without any weight or feel, just the lowering of hit points on the enemy, their combat suffer from an almost complete lack of immersion and sense of peril in comparison.