Wenlin is great, but their aversity to online ordering means someone needs to be pretty dedicated to getting it. I also think they're better for research than flashcard based study. ZDT is nice for free, but pretty flaky if used heavily in my experience. I don't think the desktop market really has all that many effective competitors, and the fact that you have a simple online ordering process puts you light years ahead of Wenlin. Granted they could fix that easily, but they don't seem to have much interest in that in the years I've watched.