We bought the Paragon 8oz popper 3 years ago during an Amazon Lightning deal for about $365. Super happy with it.
It's built like a tank, has lifetime warranty, has a warming element under the bottom and it super easy to clean the entire thing is made of stainless steel sheet metal that wipes down with a paper towel and water. The kettle is thick with non-stick coating. We sometimes will use glass cleaner on the glass sides and plexiglass doors when we don't plan to use it immediately.
The unit dissembles with ease to clean. The build quality, built-in warming rack and lifetime warranty are what had me pick this over a Great Northern or other "China" brand.
I had decided that for this appliance, I would pay a premium, wanted USA built and a good warranty. The left me with Paragon or Gold Medal as choices. The lifetime warranty and lightning deal sealed it for us over a Gold Medal model.
The trick as most have said is to use good quality ingredients. We've bought coconut oil and seeds in bulk at Detroit Popcorn but recently tried a case of Gold Medal from Samsclub.com to great results.
You need to heat up the kettle, then add the oil. When the oil is to the point of smoking, then add the kernels. They'll pop in no time, crispy and with flavor. Best part is leftovers can be re-heated for several days after being popped and still retain their crispiness.
If you have a Sam's Club premium membership, shipping for all items on their website it free. I could not find a better deal on packaged popcorn/oil packets given that freight charges are usually high since the packages are heavy.