Imperial die wax and Hornady's Unique are perhaps the best commercial lubes, both are soft waxes. Touch finger tips to the wax and thinly transfer it to the cases as you pick them up for sizing. Kiwi "Mink Oil" boot treatment is a virtual duplicate. Easy to get for not in Walmart's shoe department. Ditto other boot treatments such as Snow-Proof, etc. They all work very well, clean and quite easy to remove from fingers and cases.
I know KY Jelly works but, as usual, don't let it dry before insertion. Other alternates include Chapstick lip balm, Bag Balm and other nursing mothers nipple creams with lanolin, hand soaps that include lanolin, the wax rings for toilet bowls, electical wire pulling lubes (Gardner-Bender, etc.), auto door lock lube sticks, bowling alley wax, etc.
Lots of gooey, thick, sticky petroleum stuff like STP works but it's all a mess to work with and clean off. Ditto spray Pam and its twins. I never found an auto crankcase oil that worked well as case lube but I only tried three or four; they were "stuck case city" for me. ??
I once used WD-40 on handgun stuff for easy sizing in carbide dies and to avoid galling; for that it was okay. But I wouldn't suggest it for bottle neck cases unless you have a 'stuck case remover' handy.