Ashleigh,
First of all, good luck tonight with the snow storm!
I am new to chickens; I got my first pullets last fall. They were 20 week old Golden Comets (red sex link). They are fabulous egg layers. I get 3-4 large to jumbo size eggs/day from 4 birds.
I just recently got some chicks, both bantam and standard. At one week old, the bantams are about 1/2 the size of the standard, and I think that is generally the ratio throughout life. According to what I have read on this site, bantam eggs are also about 1/2 the size of standard chicken eggs. So, if you are raising them for eggs, I'd get standard sized birds, unless you have space for enough bantams to meet your egg needs. The sex-link varieties seem to be among the most consistent layers. Mine layed throughout the winter.
I purchased some Silkie chicks, which are bantams, to hopefully get some pullets that will be "broody" for raising chicks in the future.
I must say, the bantam chicks are absolutely adorable!
Good luck with your decisions.