Again a vote for Tharp's first book, Trade you way to financial freedom, only. The second is imho not really written by him, but mostly by Brian June, the co-author. It's a beginners guide to day-trading written in the hype-era 2001. Tharp has added two chapters and much ads on his courses and other offerings. A third is currently promoted heaviliy elsewhere, but I remain very reserved on Tharp. Strange, but snake-oil comes to my mind thinking off him.
Douglas is down to earth psychology. Both book somehow overlap, but are good to read. So I'd recommend reading Douglas first, then Tharp's first book.