In Romeo and Juliet, why does Lady Capulet think Paris will make a good husband for Juliet ?

Because he is from the upper crust of
Veronese society (as his title indicates), courageous, young, noble, and a gentleman who will
supposedly makea happy bride and share his wealth with her,believes thatis the ideal husband for
her daughter. She refers to his bravery in Act 1, scene 3 when she first speaks about Juliet
considering him as a suitor:

Thus then in
brief:
The valiant Paris seeks you for his love.

She repeats these good tidings in Act 3, scene 5 and says:

Marry, my child, early next Thursday morn,
The gallant, young and noble
gentleman,
The County Paris, at Saint 's Church,
Shall happily make thee there
a joyful bride.

In the first instance, Juliet agrees to
her mother's request to give Paris a look over but states that she will not do more than what
her mother wishes her to. Juliet's response means that she will not necessarily take any
particular interest in Paris but will do just enough to satisfy her mother's request. She is
not, therefore, prepared to consider marriage yet.

In the latter situation,
Juliet bluntly refuses even to consider her mother's appeal. Oblivious to her mother, she has
already marriedat this juncture. Juliet later gets into a heated argument with her father who
shocks his wife by vowing to throw his daughter out into the street and disown her if she does
not follow his command.  

Juliet, as a ruse, tells the nurse to inform her
mother that she is going toto "make confession and be absolved." She is, in fact,
planning to seek the friar's counsel about the terrible dilemma she now finds herself
in. 

The friar's eagerness to help by advising the distraught young girl to
drink a sleeping potion leads to a series of unfortunate events that culminate in the tragic
deaths of our two hapless young protagonists.