惊讶 (jīng yà) is the most common, neutral word for 'surprised' or 'astonished' in Chinese. It is less intense than 震惊 (zhèn jīng 'shocked, horrified') and more neutral than 惊喜 (jīng xǐ 'pleasantly surprised'). 惊奇 (jīng qí) adds a sense of wonder, while 诧异 (chà yì) is more formal and suggests being taken aback.