It depends on what criteria you are using. tl;dr at the bottom. PvE: Dark souls 1 the good: the best game world and ambiance. the bad: buggy and practically unfinished in places dark souls 2 the good: huge world, lots of bosses, and a huge variety.
But after play Dark Souls III, I changed my mind. The game is very beautiful, have good bosses and the level design is awesome. But there's too many fan service to cover some mistakes. The weapon art is ridiculous. While in Dark Souls II you have a good Power Stance, in Dark Souls III every sword looks like an acrobatic pole. Seriously, just.
I have played every Souls game (even that one) and I love Dark Souls 3. I can't stop playing it, I never get tired of it. This game is the sequel to the first souls game I always secretly wanted. Continuing the story of the world, improving game mechanics (that aspect especially!) combat and the infamous boss battles. My advice for playing a souls game is this: Don't feel bad if you can't.
Not in line with the rest of the answers, but I’ll bite. My answer would be, “Whatever the last one you play is.” A lot of people like to say DS3 is the easiest, but I wouldn’t agree, because they have the inherent bias of having started at the be.
Dark Souls III: Easiest Souls Game yet? Lets get one thing out of the way right from the start: this is NOT an article about bashing Dark Souls 3.I love the game and am paying it like a madman. It is one of the best games of 2016, even with Uncharted 4 around the corner. Now that that is out of the way, let us begin ! So, like any avid rabid Souls-Borne fan, I have been playing Dark Souls 3.