Does the airflow pattern in a hot air popcorn popper matter? / What should I look for in a popper?
All of this techniques are simply trying to get an evenly, uniform amount of heat to all kernels. If one part of the machine or blower gets more heat than the rest, then you will first start hearing the kernels pop. Then a brief silence. Then other popcorns The rest that did not get the same heat as the first ones) start popping. By the time this second kernels stop popping, the first should be burned out.

So several ways have been created to solved this. You got horizontal heat blowing, diagonal heat blowing (This cases involved a bowl like container). Then you got the vertical heat blowers. Most of this are meant to do 2 things:


Create enough heat at the bottom and blow it up until the kernels pop.
Make the popped kernels literally blow out to the top of the machine and on to a bowl of some sort.


The problem here is that, what happens if a kernel is at the bottom and it pops, but this same kernel has way too many kernels on top of it. By the time it gets blowned out, it will be almost burned or totally burned. This is the most common problem with this vertical ones (I bought one long ago). the ones left are either burned or not popped yet.

What I would look if I wanted a popcorn maker would be:

Vertical Popcorn Makers


Enough space where the kernels are heated for them to move (Since heating them will make them start jumping because of the amount of heat/energy received) and to come out quickly.
The height of the place where the kernels are left should be low to help them come out quickly.
If the space where they are is very narrow, there is a bigger chance they will burn while trying to escape their doom.
Kernels should not be thrown in with butter or any other sticky liquid, since this liquid will make them stay on the bottom and will burn more of them faster.


Horizontal Popcorn Makers


Make sure it actually spins. If they do not spin, make sure the airflow circles around the machine in a somewhat evenly distributed airflow. This should also take care of moving the kernels. If not, then kernels that stay on the borders longer will burn. For this cases, the center should have something that kicks the kernels to the borders, making sure they all pop quickly.
The space inside the machine should be in the shape of a circle so it can spin better and heat the kernels evenly. If you see a machine that starts making some socially acceptable figures that are not circles (Like a Horizontal Unicorn shaped popcorn maker) do not buy it. It will eventually burn more kernels than a circle which is the best way for airflow to work it's magic on the kernels.


Diagonal Popcorn Makers


Tips from the 2 above should be applied here. Typically they will either give you an option to spit the popcorns from the top to a bowl or from the side. In any case, watch out for space for kernels to move and heat sources.


For all the cases above, there is another small, minor, insignificant detail in regards to this machines:


Do not use plastic ones. They will not last since we are talking about a machine that will heat kernels to the point of popping them. It is much better a metal based one and have the handles be made of plastic, but never have the actual plastic be in the same place where the kernels will get heat and pop.


What I would suggest, if I may be so bold is to either use the microwave or the stove. In both cases you get the same result. On the stove you actually need to be moving the popcorn with a spoon until you see all kernels popped. In the microwave, you need to make sure they are evenly left on popcorn bag for example. Making sure they are not all push to the borders (That would make the kernels on the borders pop first and burn first before all kernels are popped) or push them all to the middle (Same effect but with kernels left in the middle).

Just some tips to look for some of this machines and ways of doing great popcorn.