Personally, while I hear the Legacy version is great (haven’t played, but have looked into it in depth as I plan to some day), the games tend to take 2-3 hours with lots of interruptions for reading in the middle of each game. The writing is great, but the length of each game and legacy aspect might not be ideal if the people with you won’t be around to finish the campaign.
Between the other 2, it’s mostly a question of theme. The mechanical differences between the 2 are small.
Personally, I love the fantasy setting. And if you want a change of map, I’d bring the Underwater expansion too. That way, if you play it enough and people want a change, you get new items, having to contend with underwater rooms and new paths to consider. But that’s without adding any significant burden rules wise.
There are people who don’t like Clank on this forum. But as a light deck builder with a sense of humour, a neat board and a race that finishes with the big bad hunting the players as they run out, I think it’s a great game that a new group should enjoy.
Some alternatives, complementary welcoming games for 4: Colt Express (programming game about robbing a train with a cool train model), If you don’t fear a 3 hour story: Forgotten Waters (feels like there is a lot of components, but each player is only looking at one or 2 counters, the story is a delight and it can mostly be explained as you play), Treasure Island (one player hides a treasure the other pirates try and find before the first player escapes and recover it themselves. Fun drawing on your mini maps as you get clues).