Zoom climbing to stall isn't really an efficient way to climb. You should climb by speed, not by angle.
There are graphs around that show the optimal climb speed for various planes but the general rule of thumb is that heavier planes climb best at higher speeds. Find out the optimal speed for your plane and climb at the highest angle you can maintain that speed. You'll climb much more consistently fast than by nosing as high as you can go until you stall.
If you change the camera angle to the virtual cockpit (first person, no actual cockpit view) there'll be two icons, one that you can move with your mouse and a smaller one that indicates where your nose is actually pointing. Generally, the closer that icon is to your mouse icon, the more efficiently you're climbing.
Also sideclimb. Kind of paradoxically the planes that benefit most from an altitude advantage also have the worst climb rates, maybe because they tend to be very heavy. Turn away from the battlefield and climb at an angle until you're at a good altitude.
And finally, altitude isn't the be all end all. Speed is life, altitude is insurance. A lot of people think altitude = win and then they don't understand how they died to a lower plane. If I zoom to 5km and 200kmh and you're at like 3500m and 500kmh, I don't really have an advantage. You can easily force a head on, run away from me, or even helicopter up on me.
Altitude differences are easy to see but speed differences are what really matters. They're what's hard to spot. Sneaky players know you can fly at an angle to increase closure rate and trick pursuers into thinking they're faster than you when they're not. That kills people.