The answer to 'best water heater installation' is to hire a licensed, professional plumber to ensure the job is done safely and up to code. Water heater installation can be complex and dangerous if not done properly, so it's generally not recommended for homeowners to attempt this task themselves.
A professional plumber will be able to properly size the new water heater for your home's needs, connect it to the existing plumbing and electrical systems, test for any leaks or issues, and dispose of the old unit safely. They'll also be able to advise on the best type of water heater (traditional tank, tankless, or hybrid) based on your hot water usage and home layout.