I have more then 25 website, which web hosting services will be suitable for me?

Reseller web hosting account will be suitable for you.
A web host reseller account is a web hosting account that allows you to create hosting packages to sell to your clients. You can also host multiple sites of your own using the disk space allotted to the one hosting account.

Reseller web hosting account come with a reseller-level control panel that allows you to create your own packages.You can allocate disk space and bandwidth to each site on the account and change the space and bandwidth specifications if the site’s needs change.

With a web host reseller account, you handle account setup, billing, and (usually) support for your clients. Your web host provider maintains the servers and answers your support questions

cpwebhosting.net Reseller web hosting account can fulfill your requirement and have the above mention features. For more info. click on Reseller Hosting Plans to sell both Windows Hosting and Linux Hosting Resources with CP Web Hosting

What is advantages and disadvantages of having a reseller account?

Advantages
*You can have more flexibility with your web hosting accounts.
*You can save money.
*You can earn more revenue at little cost to yourself.
*You can focus on customer support and leave technical support to your web host.
*Your web host, not you, absorbs server maintenance costs.

Disadvantages
*Your service is only as good as your upstream provider. If the server is frequently down, for example, you may lose clients.
*If you ever have to change web hosts, the move will be an inconvenience for your clients as well as for yourself.