The commission split is the number everyone asks about first. It's rarely the number that matters most.
What to actually compare
A "100% commission" brokerage usually means a flat desk fee instead — do the math on your expected volume before assuming it's cheaper.
Some do, some don't, and some charge extra for the leads they do provide. Ask exactly how leads are assigned and what they cost.
Ask to sit in on an actual training session before you sign, not just read the brochure description.
A managing broker who never answers the phone is a bigger problem than a slightly lower split.