I've listened to Dave Ramsey's CDs, read two of his books, and watched dozens of his shows on the Fox Business Channel. Never saw him recommend specific stocks or brokerage houses. His advice is to get with a financial advisor who will teach you about investments, not sell them to you. One of his cardinal rules is to never invest in anything you don't fully understand (and can explain to someone else). It would be totally out of character for him to endorse a brokerage house.
Regarding mutual funds, he says to research their histories and make sure they've got a prolonged record of success. He invests in one mutual fund that has never had a down year in over seventy years. That's a track record.