I will recommend you Oppo F7. It comes with a superior processor with a good amount of RAM assuring that the device can run buttery smooth even while multitasking. It draws its required energy from a 3,400mAh Li-ion battery which might be sufficient for a day.
For the selfie lovers, the smartphone offers an impressive 25MP front camera.
You can also check the complete comparison here: Oppo F7 vs Vivo V9 vs Huawei P20 Lite vs Asus Zenfone 5 (8GB, 1.6GHz)
I will suggest you go for the Redmi Note 5 Pro 6GB variant.
It provides you with the most amount of RAM (i.e., 6GB) in the price range and still manages to offer a bigger battery than the rest of the two smartphones.
Sporting a 5.99-inch IPS LCD, it comes with a metal case body and has a thin-bezel design. Under the hood, there is a Qualcomm Snapdragon 636 SoC (8 x 1.8GHz). With 12 MP + 5 MP Dual Primary Cameras you can capture images of 4,000 x 3,000 pixels. Along with the front camera, an LED flash makes sure that you can make video calls at night. It consists of a 4,000mAh Li-Polymer battery which supports quick charging and equipped with a wide range of robust features.
You can also check the complete comparison here: Honor 7X 64GB vs Xiaomi Redmi Note 5 Pro 6GB RAM vs Huawei P20 Lite vs Samsung Galaxy A6 Plus
I will recommend you Huawei P20. It might come with a 5.7-inch IPS LCD display which has a screen resolution of 1,440 x 2,560 pixels powered by two Quad-Core Cortex A53 processors (2.4GHz + 1.8GHz) aided by an 8GB of RAM. The expected camera setup at the back might be 16MP + 16MP. With an onboard memory of 128GB, Huawei P20 will be a good choice.
You can also check the complete comparison here: Xiaomi Redmi Note 5 Pro vs Honor 9i vs Huawei P20
Huawei P20 is the best choice out of the given choices as it offers a much better 4 GB RAM, a better processor performance, better 64 GB storage performance and great overall specs and configuration.
Let us analyze the details of comparison among the given devices:-
1) Huawei P20 comes with a much better HiSilicon Kirin 970 Octa-core processor, in comparison to Qualcomm Snapdragon 626 processor in Vivo V9 and HISilicon Kirin 659 Octa-core processor in Huawei P20 Lite.This can be proved by comparing benchmark scores of the three devices:-
Antutu Benchmark scores of Huawei P20 is 213,000 and in Vivo, V9 is 67,113 and for Huawei P20 Lite is 75,400. (Higher the benchmark score better the processor performance).
3) In terms of camera performance, all the three device performs really good
But, Huawei P20 is the best choice as it offers a great 12+20 MP dual primary camera with Dual LED flash and 1.8F aperture size which clicks great outdoor and indoor shots in all lighting condition.
In terms of front camera performance, all the three device comes with equally good 24 MP front camera which clicks awesome Selfies in all lighting conditions.
4) Huawei P20 comes with a much better 3400 mAh battery capacity in comparison to 3260 mAh battery in Vivo V9 and 3000 mAh in Huawei P20 Lite.
Thus, It is now clear that Huawei P20 is an overall best choice in comparison Vivo V9 and Huawei P20 Lite.
You can check all the details of the specification of the given devices through this link Huawei p20 vs Vivo V9 vs Huawei P20 Lite