Are you looking for a chair comfortable for long gaming sessions or good looking?
I ask because it is easy to mistake what feels good with what is good for your back.
Armrests should not be important for any person that has long game sessions (arm should be on the table where the keyboard and mice is, armrests can be a backup but should not be the main resting location).
Lumbar support is great as long as it does not deform on pressure from your body (thats actually worse than no lumbar support at all) The reason is because it might lead you to have a straight back UNTIL the lumbar position, where your back will deform creating pain over time.
Also, you want a hard back for the seat and if possible with it being strait with head rest.
http://www.haworth.com/docs/default-source/documents-files-very-task/ergonomic_seating_guide_handbook-pdf-13337.pdf
An interesting article thou I cant agree with all of its claims.
Bare in mind that no matter what the chair is, your sitting position should always be straight up with 90 degree angle between legs and torso/head.
This is required so the maximum amount of oxygene arrives to your brain, keeping your body active and your brain ready to work.
Finally, even if you get the perfect chair, you will still have to do stretching and exercise from time to time. Constant sitting is really bad.