If you are writing of the main service, it depends on the number of fixtures, the Municipal water pressure, and the distance from your house to the main. Generally, a typical residential service handles three toilets, five sinks, two shower/tub combinations, a washing machine and a dishwasher (hose bibs do not count). Standard municipal pressure is ~60 psi, but can go as high as 80 psi (and if it does, you want a PRV on your system). Under those conditions, a 3/4" copper service feeding a 5/8" standard meter is adequate. Note that your rates are based, typically, on the nominal meter size, so it could be somewhat costly to upsize. However, if you have a large family, use a lot of water, have tenants, or similar, moving to a 1" service to a 3/4"meter could be useful.
We have a 1" service as the house has 4-1/2 baths, and so forth. However, the service is galvanized iron installed in 1928, and is on its last legs. If we replace it, it will be with 3/4" copper.