I need to measure the temp of a water solution with 1 decimal accuracy, so it needs to be waterproof as well. That means in my case the PT100 is the way to go right?
No, and not necessarily.
It is commonplace to put temperature probes into thermowells. No waterproofing needed.
Now that we are in the 21st century, I'm not sure you would ever use a PT100 in favour over the DS18B20 unless you had persuasive reasons in the light of the shortcomings of the latter.
The DS18B20 operates from -55 to 125C. I don't know what the range of the PT100 is, but it's a lot more.
I believe the fastest rate at which the DS18B20 can return data is about once a second. This is because it essentially talks in plain english while the PT100 is just a resistor and therefore can be read faster.
While the DS18B20 can be had in a waterproof capsule, I have never seen one sensibly usable in a high pressure fitting. The PT100s I have are are a common type, being 1/4" BSP screw-in devices and are OK for use wet in mains-pressure water service.
Against this, the PT100 usually costs more and involves more peripheral electronics.