>>713170158NG2Black is a great entry point, you could also buy the Master Collection, which has all three games. It has Sigma2 is almost identical to 2Black, aside from the obvious graphic change, and both are the easiest games in the series, you can start on Acolyte, but I'd recommend starting on the Warrior difficulty if you want at least a little bit of a challenge.
NG3RE is the only one with QTEs, which might be a little jarring at first, but the prompts always have the same inputs, and are largely performing normal actions (sliding, jumping, slashing etc). The final boss of the game isn't a QTE, but there is a QTE after the final fight.
This game has the hardest normal mode, and has new rules that the first two games didn't so it's a bit harder to get into, but incredibly rewarding once it clicks. It also has a "red flash" mechanic similar to Nioh2, for countering certain attacks leading into "Steel on Bone" executions.
Whatever you choose to play, I hope you have a lot of fun.