EDIT TO HIGHTLIGHT WHY I MADE THIS THREAD:
One advantage is the circumference of a 27.5x2.1" tire is about the same as 700c32c which means a much more comfortable, larger tire without sacraficing speed.
The spokes are shorter which means a stronger wheel.
With a similar circumference, the chainring size don't need to be changed to get the same pedaling effort.
Also, the same circumference means the frame geometry won't have to be changed to eliminate toe overlap. (The experience of turning a corner won't change.)
Wider tires means better traction which means better braking.
To summarize, same speed and steering as 700c while having more comfort, better braking and stronger wheels.

Devinci Cartier

Raleigh Redux

Masi Strada Vita Uno

Kona Dew

Louis Garneau M1

KHS Urban X

Brodie Robson

Silverback Scento Metro

Marin Nicasio RC

PLUS HYBRIDS (with 27.5x2.4" or larger tires)

Breezer Midtown

Brodie Torque

Surly Bridge Club

I could include the Specialized Roll, Marin Stinson, Felt Vera Cruz and Cannondale Treadwell although those have a laid back design for leisurely riding. And the Cannondale Bad Boy has a one-sided fork which I could care less about. Interesting too that the electric bike designed by motorcycle racer Erik Buell has 650b wheels (Fuell Fluid-1). Schwinn also has the unusual dual-suspension hybrid called the Solana and beach cruisers Costin and Hornet.



ANOTHER EDIT: I find the Breezer Midtown 1.5 very interesting. First, because of the Kenda Kwick 2.4" tires. Second, it has an aluminum frame & fork. (It also has Shimano hydraulic brakes and Shimano hubs. And it's under $1K.) I'm tempted to sell 2 bikes to buy one. The only thing I might change is the gearing to 42/32/22 and XLC PD-C07 or PD-C08 pedals.

AND ANOTHER EDIT: Forgot to add the UK models of the Raleigh Strada. (I wouldn't bother with the cheaper ones with the threaded headset but whatever.)