Most people forgot to tell about the best feature available in Xiaomi phones(not specific to redmi only but all phones) - Mi Find Device
This feature makes it very simple if someone steal your phone. Generally people stealing phones, immediately format so that it cant be tracked. But if Mi device feature is turned on in your device, phone needs your mi account username password to unlock. If the person starts using phone without formating by changing sim card, phone can be easily tracked from mi cloud website and it shows currently using phone numbers to you. The only condition is Mobile data should be on. Someday user will on it and get caught. If formatted phone will be useless to him/her as he/she dont know password for mi account.
This feature can be found in setting-> Mi Account(Log In) -> Mi cloud -> Find device.
turn it on. This feaure is same as found in apple devices
redmi 4 is adorable phone under this prize m using redmi 4 previously and now m using I phone 6s and you know what now I realize tht how much better my old phpne was in my opinion you should go for redmi or any phne of xioami