Change to 3/4" full port ball valve, $20-40 parts online or box store, easy DIY job (see video below). Will do much better job draining solid build up in the tank. You should drain it at least once a year, more often depending on your local water quality.
Also replace anode rod annually, cheap insurance.
I was told by a very experienced plumber to go for a high quality water heater, Bradford White is the best and still made in America, AO Smith is next, Rheem is garbage. Also add an expansion tank with your new unit install.
