A voltage divider can work well if:
- Absolute accuracy is not that critical
- The 5V source supply is stable and accurate
- The current load you put on the central point of the voltage divider is 100 times less than the current you put through the two resistors of the divider will allow for ~1% variation
- You use decent 0.1% or 1% resistors in the voltage divider
- And you place a capacitor across the lower resistor in the divider to filter some of the voltage changes that are caused by sudden changes in the load current.
A very simple way to get a very decent reference is to use what is called a "shunt regulator" or "voltage reference" IC. One of these would connect to GND and to a pullup resistor to the +5V supply. The top side of the reference would be your stable voltage. If you need 1V you could look at the Analog Devices ADR510ARTZ. You can shunt up to 10mA through this part.
This picture from the Analog Devices data sheet for the ADR510 shows the typical operational behavior of the shunt type regulator.
Keep in mind that the shunt regulator will adjust the amount of current that it sinks (IQ) in order to keep the voltage drop across itself equal to 1V. The size of the bias resistor (RBIAS) sets the nominal current through the resistor/shunt regulator assuming no load current (IL). Once that operating point is established if the load is such that it wants to sink current then that additional current will be supplied through the bias resistor. If the load wants to source current then that extra current gets sunk through the shunt regulator.
As with any linear regulator (shunt like this one or other series pass type regulators) power dissipation is always something to consider. So if the load current nominal value is say 100uA because it just feeds impedance loads it would not be necessary to have there being 10mA flowing through the shunt regulator all the time. On the other hand if the load current had a dynamic change of say +/-5mA during operation you would want carefully pick the bias resistor such that the current variation to the load keeps the shunt regulator within its operating range. For the ADR510 that operating range of shunt current is from 100uA up to 10mA.