Search:

Google Always.

Bing is a Search Engine but not popular as Google

Following Factors you should follow in on-page SEO
* Keyword Optimization
* Title Tag and Meta Tag
* Inbound and Outbound Links
* Image Alt Tag Optimization
*URL
* Content Optimization

Bing
yahoo
baido
yandex
duckduck go

For Key word analysis Google keyword planner or keyword search console is best.

On Page SEO means Working on our page SEO Process like Technical SEO, Content Optimization, Title Tag, Meta Tag, Alt tag and etc,.
Off page SEO means Working on outside of our web page like Link...

Follow the Google Bot Algorithm, According to this we have to follow
1. Quality content
2. Technical SEO
3. Backlink
4. Page Speed
5. Mobile Optimization

Do follow - Passes the link juice between source and destination
No follow - It Doesn't passes the link juice.

White hat SEO is Process of follow the legal way to ranking our website in SERP. The legal ways means just follow the Google algorithm of Google Bot.

A/B Testing is comparison method of 2 inputs.