Hi,
Which operating system is widely used by cheap web hosting providers ?
Linux as it’s as cheap as it gets, free 
Linux (Redhat / Centos / Ubuntu) are probably the most common for cheap hosting providers, Windows tends to be more costly due to the licence requirements that it has.
Generally hosting companies use Linux Centos. This happens to be a free OS and the most widely used on shared servers. However, shared hosting companies also use windows OS. There’s a licensing fee involved however, license is server based so they would charge you extra for the windows package as compared to linux.
In any way you need to understand that operating system web server is not enough to start web hosting, you also will need some kind of control panel and billing system to manage.
Linux is most recommended by many hosting providers on shared environment for smooth results and is relatively cheaper than Windows, Windows is a bit costly due to license requirements
- i would like to suggest you to go for linux because linux is the most recommended operating system by many hosting providers and it is relatively cheaper than windows, window may cost you little bit expensive due to license requirements.