Well there are variated websites which has these. Since you have not mentioned whether its offline and online then you may opt to Google and you know the drill to avoid em shady cr(a)ck(e)d ones. Keep safe everyone.
Well it depends on several factors: the need (what for?), the reception (is tnt or dito reception good in your area?), type of user (heavy? light?), budget , model phone (optional).