Ok, so I only ever had one kind of incubator but that is because I *love* it. It is not cheap but I have used it for 8 years now and the original one is still working. I bought another one so I could have one going with the egg turner and one without egg turner for hatching days. This is when I have eggs at different stages in the 'bator. If you put them all in at once and they are all the same species one bator will be enough becuase you take the egg turner out when hatching days arrive for everyone at the same time.
Mine is this one:
https://incubatorwarehouse.com/hova-bator-genesis-1588-advanced-kit.html
Mine came with the yellow egg turner and rails and I like those a lot - they hold 41 eggs Guinea or chicken eggs. I think you can click on the choice of egg turner when you scroll down and if you want both chicken and quail size rails it adds 30.- to your kit for a total of 240.- today. I think the price has gone up a little bit since 8 years ago.
And I also super-duper love this thermometer:
https://incubatorwarehouse.com/incubator-remote-thermometer-hygrometer.html
I don't think I had the thermometer in the first year and we hatched our original flock without it. The thermometer/hydormeter is very cool, though, in that it has a max / min memory and will let you see what the max/min temperature and humiidty was since you last reset it. Also, the battery lasts super-long. I have one in the coop that has worked for years. I like to see how hot or cold my babies got while I was at work or away for the last 24 hours. I tend to reset it every night after checking it.
The incubator is nice since it has that big window on the top so you can see the eggs and keets (hatching) without opening it, even though you have to open it to add water , if needed. I always add warm water, of couse, and try to have the water filled before the hatch starts.
It is a bit frustrating to clean the thing, since it is just styrofoam but that's ok. Overall I am very pleased with the functionality and ease of use. I just set the temperature, fill the water channels, add the eggs and plug in the turner and 'bator and keep an eye on it every few days to refill the water as needed. At hatch time, I put the eggs in cartons, take the turner out, and put the eggs back in. Add more water, close and watch for keets!
We only have Guineas with thick egg shells, so I do not candle until about day 7-10 to see red veins. Chicken eggs are thinner, I think, and you can see something sooner. I use a regular flashlight to candle them and have not bought a special light for that after the first year. God knows where that little light went.
There are many different opinions and likes on incubators out there, so you will probably get some other great posts on here.
Watching the hatch through my 'bator window: