I would suggest Samsung Galaxy S4 as best mobile in market currently. It has more features than other smartphones which get released with this. Check the specifications of it at http://www.gsmarena.com/samsungi9500galaxy_s4-5125.php . Recently i too have bought Samsung galaxy S4 locked mobile at low cost. I have unlocked it using unlock code from the site http://www.unlocking4u.com/samsung-i9500/rs6wp9/ ,to use it with any other GSM networks.
If phone, spec wise, Samsung Galaxy S3 is good to go. If you like small and spacious, iPhone 4s or iPhone 5.
As in a phone or phone service?