My choice
Ok there are several key questions to be asked,
First who is my enemy? Will I have to engage highly manouverable fighters like F18s/ F16s ect operating close to my home base or will I have to engage swarms of low flying cruise missiles and penetrating strike aircraft possibly a thousand miles plus from my airfields.
Second what can I afford to buy?
Third what is the foreign policy of my country? If I expect to operate from home bases with good support infrastructure then the Foxhound would be a better bet , if on the other hand I am expecting to be an expeditionary force then a aircraft capable of operating from austere forward airfields and at the end of long supply chains then the Mig-35 would be better.
Although performance is important, the questions above are only some of the others that are asked when air staffs draft requirements for new aircraft.
For my money I would hedge my bet with a Hi-Lo Mix of both.
Incidentally the origional Mig-25 Foxbat was designed to intercept the SR-71 and the cancelled XB-70 valkerye, however the Mig 21 Foxhound was designed to counter some of the short commings of the Mig 25 and expand the capabilties of the PVO-strany(Soviet Air Defence Command) to defend the vast northen tacts of the then USSR. The foxhound had more fuel efficent engines fitted to improve endurance, more capable radar to allow the tracking of low level targets, the addition of datalinks to integrate the foxhound into to soviet air defence network and new long range active radar homming missiles.