I’ve been collecting sensor logs from different CraftBeerPi3 users.
Here is a plot of the temperature sensor signal from two different systems plotted together. One uses the ds18b20 one wire sensor and the other uses a PT100 sensor.
The PT100 signal is much more noisy. It makes sense, the signal the pt100 measures is very weak and is then carried in analog form over wires before being amplified and converted to digital form. The DS18B20 is converted to digital form at the point of measurement.
PT100 thermocouples can be very accurate but it requires careful routing of wires, shielding etc.
Don’t take it for a absolute truth about these type of sensors, just an example of what you might see and get. Both signals and sensors are more than enough for brewing.