I know you asked for 20 eggs capacity but I have been using the Kebonnixs 12 egg capacity for a few months and it's almost flawless. I can fit about 24 Serama eggs. I bought 3 more of them just because of the hatch rates and ease of use. They are very quiet until the eggs rotate obviously. Then you hear a little egg shuffle.
The biggest flaw is it has a very smooth plastic bottom. Hello spraddle legs. Thankfully I use a double incubator set up. Basically I have all of the incubators running on auto rotation indefinitely and add eggs daily. On day 18, the eggs go into my own special homemade incubator that is just for hatching. It has a nice flooring to prevent any leg issues and I can keep it at the perfect humidity all the time. That humidity consistency gives me time to open and close the incubator without any problems. I always strongly recommend the double set up because my hatch rates on the Seramas are at least 90% with the eggs always being fresh in the rotation. You can combat the issue by putting a shelving liner in on day 18 if you don't want a double set up.
Honestly I love these little incubators. I figured I could return it if I didn't like it but they have just done so good by me, I thought I'd recommend one to you to try.
The best incubator by far for that egg capacity is the Nurture Right 360. I have two and am in the market possibly for a third. They have never let me down, keep consistent temps, super quiet and hold up to 22 eggs. You can’t go wrong for that price range and quality.