Pre-determiners are normally placed before an indefinite article + adjective + noun to express an opinion about the noun they modify. Such and what are used to express surprise or other emotions.
- What a lovely day!
- She's such a beautiful woman.
- You can't imagine what an incredible meal I just ate.
- I've had such a good time today!
Rather and quite are commenting words, referring to the degree of a particular quality as expressed by the adjective that modifies the noun. They can express disappointment, pleasure, or other emotions depending on the adjective in question. In British English, rather is used as a pre-determiner. In American English it is only used as an adverb. The examples given below are British English.
- It was quite a nice day.
- He's had quite a bad accident.
- It's rather a small car.
- I've just met rather a nice man.