I use a Brinsea Octagon for both - the 20 will fit 9 of my goose eggs (and the 40 is just twice the size so 18 goose eggs). Chicken eggs vary - as you can tell by the name, it's supposed to fit 20 but I think those are small chicken eggs. I love it for incubating, am less convinced for hatching (the fans dry out the membranes and you can't get it really humid in there) so might buy an alternative for that. I've got the full on version - with the cradle and humidity pump but since I'm hatching waterfowl at the moment, I don't really need either as I turn by hand and run it dry.
H