Questions About Installing A Replacement Gas Hot Water Heater Myself

My daughter and her husband are buying their first house and it has a 19 year old natural gas hot water heater that I think should be replaced as soon as they move in. It looks new but really is 19 years old which I believe is about twice its normal life expectancy. I'm retired and pretty handy so I'm thinking about replacing the tank myself to save them some money since they are shelling out a lot of cash to purchase the house. Since replacing a gas hot water heater is something I've never done I have several questions for the members of this forum. They are: 1. With money being a consideration is a Rheem gas hot water heater a reasonable choice? Any particular model or series?