Tom Hindle: This is a game of hypotheticals, and this trade is an entirely seismic thing. Point is, there's not really an equivalent. The closest would be an imaginary deal of Harry Kane for Kylian Mbappe. Like Davis, Kane is absolutely elite - but has probably already played his best stuff. Meanwhile, Mbappe is undoubtedly one of the game's best, but limited by his defensive work rate (insert joke about Doncic's reported diet here).
Jacob Schneider: There's no proper equivalent in terms of talent, but in terms of a trade out of nowhere without a player being aware, the MLS comparison would be Dax McCarty's trade from RBNY to the Chicago Fire in 2017. Nobody saw it coming, and he was baffled after being moved unexpectedly. If there was one transfer of a similar nature that caught the entire world by surprise, perhaps Luis Figo from Barcelona to Real Madrid, or Robinho from Real Madrid to Man City? Unfortunately, soccer transfers often lack surprise, so there isn't a definite comparison.
Ryan Tolmich: Vinicius Jr for Joshua Kimmich. This is trading an attacking marvel, one who is still young enough to keep getting better, for an experienced but versatile defensive presence. Vini, like Luka, has proven he can carry a team pretty damn far, although there are still hurdles to clear for either to be declared the best player in their respective sports. Kimmich and Davis, meanwhile, are title-winning players but also aren't necessarily THE guy on those title-winning teams. You can see why Real Madrid would be extremely hesitant to do this deal, just like you an see why the Mavericks should have probably been pretty hesitant about their own trade.
Alex Labidou: This is the worst trade in decades. Doncic is a MVP candidate who is 25 and has at least 10 years of basketball left in him - and he will revitalize the Lakers. The best soccer equivalent might be AC Milan letting Andrea Pirlo go to Juventus for free. At the time the Rossoneri thought Pirlo, similar to Mavs and Doncic, wasn't able to stay at peak fitness and was past his best. He proved them wrong, winning four Serie A titles among other trophies. It was a move that was so surprising, that Juventus icon Gianluigi Buffon said, "When Andrea told me that he was joining us, the first thing I thought was 'God exists'. A player of his level and ability, not to mention that he was free, I think it was the signing of the century."