Specifically in the past 4 years? I'm curious as to why that specific time frame. You mention Fallout New: Vegas though, which was released in 2010, a bit more than 4 years if you ask me
So, excluding The Witcher 3... hmmm... for me then I'd have to go all the way back to Dragon Age: Origins. More recently I've also enjoyed Fallout 4 a lot, more than 3. I guess that would be the most recent one I really liked, and I still haven't finished it. There's a bunch of recent RPGs I'm curious and heard a lot about, but just never got to play (yet). But yeah, overall, DAO would be the one I enjoyed the most until The Witcher 3. I really like TW3 but I still prefer DAO, since I just prefer it (in general, with a few exceptions) when I get to create my own character rather than playing a fixed / pre-established one. I tend to 'connect' with my character, therefor the game as a whole, if I can create them and some form of backstory is provided as well. And it would be bonus points if I can also choose some of that backstory, similar to... let's say the psychological profiles and the pre-service history we can choose from in the original Mass Effect (Spacer, Earthborn, Colonist / War Hero, Ruthless, Sole Survivor).
I must say, however, that if the Witcher series would have allowed us to create our own Witcher character from the start then I might have considered at least specifically The Witcher 3 definitively one of the greatest games of all time. But since I can't really connect with Geralt I can only appreciate other aspects of the game (music, general story outside of Geralt, game's lore context / setting, voice acting, script / dialogue quality, game play mechanics, game balance, visuals, etc). He (Geralt) did grow on me over time though, but prior to The Witcher 3 I had never played a single Witcher game (despite actually buying the first one on sale over at GoG.com long before TW3 was released), so when I first played TW3 (and for a long time after) I remained generally indifferent to him, not exactly because I was simply ignorant of everything about him (I had read a good amount of lore concerning him and his background info before buying the game) but I just... I dunno, couldn't get "into his shoes"; he just didn't "click" with me. So I merely enjoyed the game from my point of view as a gamer, rather than trying to immerse myself "as him" like a good RPG would allow me to.
Anyway, so yeah, DOA as my favorite; or more recently with Fallout 4.