Help between 2n2222 and 2n2222a?
Both parts are about the same.   The 2n2222A is a slight bit better in terms of Vceo, Vcbo, Vebo.  But if you are not planning on stressing the part (higher voltages, etc) both will work well, especially for simple switching and logic circuits.  The 2n2222 part is the older style part which might be the reason they are being offered at a low price.