White, yellow, bicolor?
su, se, sh, or (sy)synergestic type?
Cold soil germination?
Wet or dry?
Under 70 days? (10 weeks growing)
Usually the longer the growing time the bigger the ears get.
Mid season types take at least 75 days and longer to harvest
Lot of choices with sweet corn including # of rows per ear. Many people today want a small kernal. Corn varieties can vary from 12 to 20 rows per ear with 14-16 being pretty standard
Treated seed?
Helpful for wet soil or insect resistence
Just where are you located?
Butter & Sugar was always a favorite...an older su type bicolor @ 75 day is usually found on seed racks. We grew and sold that commercialy for many years.
Trinity, an early variety from Johhny Seed I also grew before. Been around for a while now. A popular short season bi color se type @ 68 days. Johhnys now recommends their variety Sugar Buns (se) for a longer harvest time.
Harris Seed has some real good early choices both white and bicolor. Their # 1 selling early bicolor is Sweet Chorus and the Harris 1001 @72 days is a small (refined) kernal 8 inch ear. Earliest all white variety they have is called Spring Snow @ 66 days with 5 ft stalks and small 6.5" ears. All of these are the se types. (sugar enhanced)
There are also several bicolor supersweets (sh types) under 75 days they also offer. These need growing isolation by time or distance to avoid being cross pollinated with other types.
I barely ever see anyone grow an all yellow, especially to sell anymore but they are still out there. Harris has an early sh type called Northern Xtra Sweet @ 67 days and Johhny and Harris both sell a supersweet (sh) yellow called Vision @ 75 days.