The Aquacomputer High Flow series are the most accurate flow meters out there marketed for computer cooling loops. You do have a point about the mechanical rotor. I don’t know why they decided to change from a differential pressure flow meter to a mechanical rotor, but I suspect it allows a wider measurement range.
If you want a flow meter with no moving parts that can handle 1000 l/h you may have to look in the industrial market.
KEYENCE has many varieties available. Electromagnetic, Karman Vortex, Paddle Wheel, Floating Element, Thermal, Differential Pressure, Ultrasonic, and Coriolis. The best method for a computer cooling loop is probably Ultrasonic. They have a guidebook that explains all the different types with pros and cons. I tried to upload it but the file is too large for this forum. Note - I had to make an account there to be able to download their technical documents. These flow meters are not cheap. The FD-Q10C is an Ultrasonic flow meter that can measure up to 1795 l/h (with a 9.525mm diameter orifice). Market price is about $900.