to choose enterprise search center site collection or basic search center sub site

hi,

 in my web application there is a requirement to implement Search.

so, whats are he criterias, i need to look for when i implement ent.search.

1) Should i create a  ent.search  site collection template and  provide it's home page link [ with search box,refinement panel  etc] in my  web appln's  top navigation ?

OR

should i  create a  simple basic search center sub site, and provide the   url  of this  basic center sub site's link on the top navigation of my web appln.

pls advice.