Ok, if you want to change the rules to still in service or mach 2 etc, you are aware of the F4 Phantom stats aren’t you?
This again doesnt place the Mirage as above other similar tech aircraft...
Using the criteria of: Modern, fast, high kill ratio etc you would find the answer is the USA*, and not any country in Europe.
For everyone else, the F4 has over 300 air to air kills.
The Mig21, also of similar vintage has 240.
*A quick look at the air to air kill ratios of the F14, F15 and F16 demonstrate this, and is further shown by the very high kill ratio of the F14 in Iranian service.