The "best key" is very much a matter of personal preference. I have been a CW op (ham, maritime, and shore station) op for about 67 years, and for much of the time used a bug, or whatever key happened to be at a station. Naturally I got used to hitting the key rather hard. When I started using paddles, this style continued. For a few decades I used a Kent paddle, which I found very satisfactory. From time to time I borrowed a few high end Swedish and German paddles from friends and used them in my shack for a few weeks. Also at Dayton, tried many keys including a long session at the Begali booth. Most were fine keys, and budget was not an issue for me. Finally, for no valid reason (since I was always very satisfied with my Kent), I purchased a N3ZN dual lever paddle 5 or 10 years ago. It was sure beautiful, but took me some effort to learn to handle it gently, instead of banging it like a bug. So look at the ZN paddles as well as others. Also consider K3TN's advise to at least try a single lever paddle. I am 80 and too stubborn to admit that I will give up on iambic squeeze keying, and go to the more logical single lever paddle. Also I would need to get rid of my dual lever paddle collection. I have both magnetic return and spring return paddles and have only a very slight preference to the magnetic ones, however some folks really have strong opinions on their preference. Also, some paddles make louder clicking noises, which some folks consider objectional, but personally this is not an issue, since for serious CW work, I use headphones. If I lost my entire paddle collection, I would personally just buy another N3ZN.
RICK KL7CW