At your height, for a hardtail, you definitely want a 29er. The added inertia also helps you hold speed better on flatter trails. The larger wheels will help smooth the trail and are better for cruising along.

The main reason for 650b on smaller hardtails is that it's hard to fit a 29er wheel in a small frame with reasonable stand-over and steering angles.

650b is common for full suspension because it's nearly impossible to fit 150+mm of rear travel with a larger 29er wheel.