Welcome to Mi Community.
Both are Good Handset. But I prefer Redmi Note 4.
Why you But Redmi Note 4...
Here is some Reason.
Xiaomi Redmi Note 4 smartphone was launched in August 2016. The phone comes with a 5.50-inch touchscreen display with a resolution of 1080 pixels by 1920 pixels at a PPI of 401 pixels per inch. Xiaomi Redmi Note 4 price in India starts from Rs. 9,999.
The Xiaomi Redmi Note 4 is powered by 2GHz octa-core Qualcomm Snapdragon 625 processor and it comes with 4GB of RAM. The phone packs 64GB of internal storage that can be expanded up to 128GB via a microSD card. As far as the cameras are concerned, the Xiaomi Redmi Note 4 packs a 13-megapixel primary camera on the rear and a 5-megapixel front shooter for selfies.
The Xiaomi Redmi Note 4 runs Android 6.0 and is powered by a 4100mAh non removable battery. It measures 151.00 x 76.00 x 8.30 (height x width x thickness) and weigh 175.00 grams.
The Xiaomi Redmi Note 4 is a dual SIM (GSM and GSM) smartphone that accepts Micro-SIM and Nano-SIM. Connectivity options include Wi-Fi, GPS, Bluetooth, Infrared, USB OTG, FM, 3G and 4G .Sensors on the phone include Proximity sensor, Accelerometer, Ambient light sensor and Gyroscope.
But it is your choice you can buy Redmi Note 4 or Redmi 3S Prime.