Any chair, despite the 'ergonomic' in its title, isn't ergonomic unless you really feel comfortable sitting in it.

Any good office chair will be adjustable to ensure a better fit and a greater likelihood of promoting good postures.

Expensive chair does not necessarily mean the best ergonomics and comfort. Smaller chair makers, even the local chair maker, have lerned from the best chair principles over the years, so Herman Miller and kinds no longer have a monopoly over great office chairs. However, good chair makers make sure their chairs are sturdy and work well for long periods.

Many online stores have 30-day, no-questions-asked return policies for high-end chairs.

Also, know this: However great a chair you get, you shouldn't sit for long durations, it is not only bad for your health, your posture also tends to tends to slouch over time.

The best office chair:  Steelcase Gesture (ball-and-socket armrests that function like a human shoulder,  big range of adjustability)

The second best office chair: Steelcase Leap (bulkier than top Steelcase model)

The best office chair for sweaty backs: Herman Miller Aeron (mesh back and seat )

The best affordable office chair: IKEA MARKUS (adjustable reclining, built-in lumbar support, great price)