Depending on what you would like to analyze, all of those scenes are full of amazing quotes.
One of my favorites in Act 1, Scene 1, is spoken by Tybalt because it serves well to characterize him. When Tybalt sees Benvolio standing before the servants with his sword drawn, Tybalt immediately thinks Benvolio is starting a fight with the servants, rather than trying to end the fight. Tybalt declares,
What, art thou drawn amongst these heartless hinds?
Turn thee, Benvolio! look upon thy death. (I.i.61-62)
Tybalt uses the expression "heartless hinds," "hinds" meaning "hounds," to assert that the servants are stupid, low-life commoners, not worth a nobleman's attention, like Benvolio. Tybalt's assumption that Benvolio would take the time to challenge individuals who are socially unimportant shows us just how quick Tybalt is to jump to violent, erroneous conclusions. These two little lines serve to characterize Tybalt as a very rash, hot-tempered person who is quick to jump to conclusions, which causes dyer consequences.
Another character revealing quote is spoken by Lord Capulet in Act 1, Scene 2. After having been sentenced and fined by the Prince in the previous scene, Capulet opens this next scene with the lines,
But Montague is bound as well as I,
In penalty alike; and 'tis not hard, I think,
For men so old as we to keep the peace. (I.ii.1-3)
In referring to his age in this speech, Capulet shows us that he fully understands just how much both he and Montague have been acting like children, rather than grown, mature men. He is showing us he firmly believes that men their age should not be maintaining feelings of hatred and keeping up a violent feud that affects the whole peaceful city. These few lines show us that Capulet is feeling guilty about his actions.
Another good passage is spoken by Mercutio in Act 1, Scene 4. Mercutio says to Romeo, "If love be rough with you, be rough with love. / Prick love for pricking, and you beat love down" (I.iv.28-29). In saying this, Mercutio is showing us his stance on love. Mercutio does not treat love as seriously as Romeo, but instead treats love as a joke, something not worth hurting over. Not only that, Mercutio is making a pun out of the word "prick" for the purpose of making a sexual innuendo. The word "prick" can mean to "puncture" or to "stab," but since it can also mean to "erect," it can have sexual connotations (Random House Dictionary). Hence, we see that Mercutio thinks of love in only sexual terms.