Dark Souls, hands down. I started playing when it came out on the Xbox 360 back in 2011. I'd been a gamer since the original NES era, so I was one of those people who got really excited over the prospect of a modern "hardcore" game that didn't hold your hand or any of that. I completed my first playthrough blind without summons, and I can definitively say that I have never had a better gaming experience than those 80-90 hours I spent dying over and over again. Note that this was before the early console patch came out that lowered the game's difficulty, so 4Kids basically always one-shot you (and I distinctly remember that fact because I know it took me over 20 in-game hours to beat them my first time around). There were so many highlights to my first playthrough, like seeing the Hydra in Darkroot for the first time (and getting rekt by infinite water blasts), falling through the trap doors in the Sewers and getting rekt by basilisks (without any knowledge of purging stones), all of Blighttown, and not realizing I had a lantern until halfway through the Tomb of the Giants, which meant I got rekt by giant skeletons, giant skeleton arrows, giant skeleton dogs, and gravity far too many times to count.

I spent the next couple thousand hours not only getting all the achievements on multiple XBL accounts, but doing everything Dark Souls has to offer. I've probably spent days ninja flipping around bonfires just waiting for someone to summon me for some jolly cooperation as a Sun Bro. It was the best feeling helping newcomers beat Beavis and Butt-head for the first time, or fending off invaders spamming WotG at us in the Tomb. I did a lot of invading too, kicking people off ledges in Sen's Funhouse, cosplaying the third silver knight archer in An** Rodeo, and doing a lot of this in the Undead Parish (made for fun roleplaying back when everyone wasn't a twink). But by far my favorite experience in Dark Souls was playing as a Forest Hunter. Nothing I've done in a video game has ever been as satisfying as invading a couple gankers in the forest and beating them 1v2 as they fish for backstabs with their Great Clubs and their TWoPs, and then channeler dancing over the host's corpse after spamming Look Skyward.

So, I basically played the life out of Dark Souls for a couple years until my Xbox finally pooped out and red ringed. It sucked for a while, but I eventually bought a PS3 because I "needed" a Blu-ray player/Netflix box. In reality, I bought it because I wanted to play Dark Souls again, which I did. So, for the first time in my life, I bought a game on two different consoles, just because I enjoyed it that damn much.