I've been using a solid and height-adjustable Proel stool for years.
http://www.proel.co.uk/in...84&product_id=5961 No arms, adjustment is done by a pin that can be slotted into a row of holes so there's no springs or shock absorbers to creak or lose tension and slowly collapse and the seat tilts a bit which helps comfort.
Before I used it I spent several years going through a variety of office-type adjustable chairs over a pretty wide price range and sooner or later found them all pretty useless in one way or another. The most expensive had the shortest lifespan before it took to creaking, slowly collapsing and making far too much noise.