Dark Souls 3 has the best weapon system and online functionality, making it the definintive Dark Souls experience. Even though 2 is probably my favorite, if I could recommend just one Dark Souls game to any random person, it would be Dark Souls 3.

The central hub and upgrading systems are also the most streamlined. The biggest complain would be that the game is too easy for veterans of the series, and some of the bonfire are way to close to each other.

Titanite Slabs are in limited quantity. I remember trying to pick one up from trading with the crow on top of the Firelink Shrine before sidestepping and plunging to my death. It was gone forever. I was on NG+++.