BVR (air and sea) is not as simple as it sounds, wondering why I am posting a picture of MiG-21? Answer is below.
I see a lot of takes on the internet where a country A has a 150 km missile and a country B has a 120 km missile so A is better than B and the case is closed

Imagine a MiG-21 with its small nose cone radar with an R-77. Can the radar even detect a small RCS target at that range? Rafale, Typhoon, J-20 and even smaller jets like MiG-21 itself might not be an accurate fix at those ranges. Throw in jamming, ground clutter, fog of war and you are unsure if your enemy is the enemy.

At those ranges, how sure you are that the target is what it is? Plus, there are other factors

• Is the BVRAAM Active Radar Homing or Semi-Active (most modern ones are Active, so one problem solved)
• RWR load out of the target aircraft, jamming suite, countermeasures suite etc
• Some missiles (SAMs) have unpowered glide final phases which are easier to out run or out maneuver.
• Mid course correction: Some missiles can have that feature and not opt in, whereas other might not.

To summarize anything, even small factors can affect how BVR missile actually performs in the real world. It depends on the target, the environment and the launcher. One funny thing is, an AEWAC with 100s of BVRAAMs is the best platform for such a thing but havent seen one.