Hatching chickens

So you can let hen to sit on eggs and incubate chickens, but you can buy incubator and eggs for hatching and set up running incubation. I chose second option... but... as I didnt found why cheaper incubator is not good and why expensive incubator is so extremly good I did first mistake, I bought 70€ incubator... but maybe not mistake... I like to do things acurate, so set everything up, put eggs in and hoped for many fluffy chickens to hatch after 21 day... I get some advices from people, best was tu put packaging around it to keep heat... then I understood that thermometers are showing unacurate values, and calibrated thermometrs cost fortune, hydrometers more... adding water takes time and cools down egs... so two minuses for cheap incubator....so far
As hatching day got closer, I even put cvt camera to see how it happen over daytime at job... despite that I think I put all set up right, just less than half got out of egs... I was informed that hatching will be poor just because of cheap incubator, but I was smarter... as I bought different chicken breeds, I put eggs in different places in incubator and different levels, leaving outer line empty... so hatching result is more true and I got interesting outcome...
If in the same incubation one breed hatches 20% and another 60%... who is porr quality?!? Incubator or eggs bought for incubation? Big question- as big as who was first, egg or chicken...
One knowlege I got: mandatory is to get best eggs possible, then check for updates for incubator, so far I decided to make mistake, to buy eggs for next try from the same seller... hoping to get better quality... I was wrong but it will be next storry...
P.s. first hatched chicken... in chinese incubator filmed online with ip wi-fi cvt camera also made in China... and I still say that result of hatch is not because of incubator only:)