Why doesn't Rosaline like Romeo? What is Juliet's opinion of Paris?

When the reader first meets Romeo in Act I he has a terrible crush on Rosaline. He is depressed and spends many hours by himself and in the darkness of his room. When confronted he confesses to his cousin Benvolio that, even though he is madly in love with Rosaline, she does not reciprocate his affection. In lines 216-224 of Act I, Scene 1 Romeo says,

Well in that hit you miss. She’ll not be...

When the reader first meets Romeo in Act I he has a terrible crush on Rosaline. He is depressed and spends many hours by himself and in the darkness of his room. When confronted he confesses to his cousin Benvolio that, even though he is madly in love with Rosaline, she does not reciprocate his affection. In lines 216-224 of Act I, Scene 1 Romeo says,

Well in that hit you miss. She’ll not be hit
With Cupid’s arrow. She hath Dian’s wit,
And, in strong proof of chastity well armed,
From love’s weak childish bow she lives uncharmed.
She will not stay the siege of loving terms,
Nor bide th’ encounter of assailing eyes,
Nor ope her lap to saint-seducing gold.
O, she is rich in beauty, only poor
That, when she dies, with beauty dies her store.

In other words, Romeo says she will not give in to his advances. She is as clever as the Roman goddess of hunting, Diana, and shields herself against Cupid's arrows. Rosaline has vowed never to give up her "chastity" and to remain celibate. Of course, Romeo finds this a terrible waste and he complains about it for several lines. It tells us that Romeo is quite a sensitive young man and that it is perfectly plausible that, after seeing Juliet, he falls in love at first sight. It also gives Shakespeare a reason to place Romeo at Capulet's party. He originally goes to see Rosaline but soon forgets her after meeting Juliet.

In Act I, Scene 3, Lady Capulet brings up the subject of Juliet marrying Count Paris. As his title suggests, Paris is very wealthy and a good match for Juliet, who also comes from the upper class of Verona society. Juliet's nurse is excited for Juliet because she believes the count a fine and handsome man. The Nurse says,

A man, young lady—lady, such a man
As all the world—why, he’s a man of wax.

By saying he's made of wax the Nurse is implying how good looking Paris is. Although Juliet is only 13 it was quite acceptable for young ladies her age to marry older men in Renaissance Italy. We never learn Paris's age (nor Romeo's for that matter) but we can guess he may be in his 20's. Juliet wants to play the dutiful daughter and she tells her mother,

I’ll look to like, if looking liking move.
But no more deep will I endart mine eye
Than your consent gives strength to make it fly.

She says she will check out Paris to see if she likes him but will do nothing without her parents' consent. Paris, on the other hand, is ready to marry Juliet immediately. He is twice seen speaking with Juliet's father about the subject. Paris, of course, is nothing in Juliet's eyes compared to Romeo.