No reason to buy the more expensive ones. It is just made out of brass and comes with other adaptors. But the universal cone shaped one that comes on the cheaper model will work with 99.9999% of cars. Wish I got the cheaper one instead.
Besides that nifty tool you need an air compressor large enough to make it work. It does work well but not 100%. You still will have to bleed the system a little. I mix up 4 gallons (2 of water and 2 of anti-freeze) in a 5 gallon bucket and fill it that way. You don't have to use it but it does speed up the job of refilling and bleeding. Along with that tool you should have a coolant system pressure tester. Other nice to have coolant system tools include:
Test strips to check acidity
A diffraction analyzer to measure the boiling and freezing points
A combustion leak detector
An Infra-Red thermometer to check temperatures
The coolant should be checked annually and replaced every 5 years. The level should be checked once a month.