If you are comparing Sihoo M59AS vs C300, you are likely trying to find a chair that feels good during long desk hours without spending a huge amount of money. I tested both chairs in my home office in the USA. I used them for typing, editing, meetings, and casual evening browsing. Both chairs focus on ergonomic support, but they feel very different once you sit for hours. One feels softer and more relaxed. The other feels more structured and adjustable. After real daily use,