Yes, Huawei P20 Lite supports slow-motion videos. It is an amazing device which offers you a 4GB RAM along with a HiSilicon Kirin 2.36GHz processor. Camera set is wonderful with a 16+2MP dual camera and a 24MP front camera.
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.
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.
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.
It is a tough competition between these two phones, one side Vivo V9 Youth has a bigger screen and better battery backup but on the other side Honor P20 Lite has a better processor, larger storage, and better selfie camera.
So in my opinion, you should go for Honor P20 Lite.
Though both phones have moreover same specification and rated as same, if you are looking for better camera than you can go for Huawei P20 Lite while if you want better battery than you can go for Honor 9i. Honor 9i and Huawei P20 Lite