I got the Ninebot/Segway ES1. Frys had them on sale for $300 about a month ago. Bird uses the Xiaomi/Ninebot m365, which is similar in many ways. The Xiaomi is faster, but if you want the faster speed, you can get the ES2, which Bird is also starting to use. The fold on the ES1/ES2 is superior -- it's simpler and faster, and the scooter folds up smaller, so it's more practical to put on the luggage rack on the train. It's a single lever and literally 3 seconds to fold or unfold. The ES1/ES2 also has an optional second battery pack which doubles the range and increases the speed. The ES2 has rear suspension, is 3 mph faster, and has rear and underside lighting. The extra speed and lights are nice, but the rear suspension adds weight and people say it rattles.
Overall, it's a really well designed product. I'm pretty concerned about the durability though. I've ridden it about 100 miles, and so far so good, but there have been several small issues with rubber coming unglued, it's starting to creak a bit, the caps on the handlebars pop out. The advertised range is also wildly overstated. It's rated at 15 miles but I had mine run out of juice at about 8.5 miles.
My hope is that the big rental companies will push Ninebot to make durability improvements, and the next version will last longer. Based on my experience so far, and what I've read online, I'm expecting maybe a 3-400 mile lifetime for this one.
If you get one, do your best not to go over any significant bumps at speed. The wheels are small, the tires are solid rubber, and the suspension has very little travel. The motor is in the front wheel. If you bottom out the suspension, the motor is going to take the hit, and it's small, high performance, and built to a low price point in China.