Fairly
She’s fairly pretty/smart.
I speak English fairly well – enough for everyday purposes.
Quite
He’s lived in London, so he speaks English quite well.
I quite enjoyed myself at your party.
The room was quite a mess.
Rather
How was the film? – Rather good. I was surprised.
He speaks English rather well. People often think he is a British-Born Chinese.
It was rather a disappointment.
He’s rather a fool.
He had a rather good idea & He had rather a good idea.
pretty
Things are looking pretty good!
You are driving pretty fast.
Considerably /significantly/ Extremely /enormously/incredibly/unbelievably/exceedingly/remarkably/astonishingly
Fairly < quite < rather=pretty